Preparation of monomers for grafting to polyolefins, and lubricating oil compositions containing grafted copolymer

ABSTRACT

A graft copolymer containing one or more ethylenically-unsaturated, aliphatic or aromatic, nitrogen- and oxygen-containing graftable monomers grafted to a polyolefin is disclosed. Novel monomers, methods of making such monomers, and graft copolymers comprising such monomers are based on reacting an acylating agent with an amine to form a reaction product. The reaction product may include more than one chemical compound formed from the combination of the acylating agent and the amine. The monomer is the graftable, ethylenically unsaturated, aliphatic or aromatic, nitrogen- and oxygen-containing compound(s) of the reaction product. The monomer may, but need not, be recovered from the product mixture. The preferred monomer is the reaction product of maleic anhydride and 4-aminodiphenylamine. Also described is a method of making a dispersant viscosity index improver. The monomer of the present invention may be grafted to a polyolefin in solutions or melts. Also described is a lubricating oil comprising a base oil and a grafted polyolefin as described above.

RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) ofU.S. Provisional Application No. 60/383,204 (“the '204 application”)filed on May 24, 2002 and of U.S. Provisional Application No. 60/383,845(“the '845 application”) filed on May 29, 2002. The '204 application andthe '845 application are incorporated by reference in thisspecification.

TECHNICAL FIELD

[0002] The present invention relates to novel graft copolymers withpolyolefin backbones. The polyolefins are grafted with reaction productshaving nitrogen and oxygen atoms and at least one point of ethylenicunsaturation.

[0003] The present invention further relates to novel monomers, methodsof making such monomers, and graft copolymers comprising such monomers.The graft copolymers comprising these novel monomers are useful asdispersant viscosity index improvers.

[0004] The present invention further relates to methods formanufacturing these novel graft copolymers. The invention still furtherrelates to lubricating oil compositions containing these novel graftedpolyolefins as dispersant viscosity index improvers.

BACKGROUND OF THE INVENTION

[0005] Grafted copolymers of nitrogenous, heterocyclic monomers withpolyolefins having pendant ethylenically unsaturated moieties havepreviously been proposed for use in lubricating oils as viscosity indeximproving (VII) agents and as dispersants for keeping the insolublematerials in the crankcase of an internal combustion engine insuspension. Among many graftable polyolefins suggested for this use areethylene-propylene polyolefins, grafted with 0.3% by weight ofN-vinylimidazole. U.S. Pat. No. 4,092,255, column 10, lines 52-53. Otherexamples in the same patent are “statistic” copolymers, which aredistinguished from grafted copolymers. U.S. Pat. No. 4,092,255, column4, lines 5-13.

[0006] Another material for use as both a viscosity index improver and adispersant is a polymer containing N-vinyl pyrrolidone and an alkylmethacrylate. U.S. Pat. No. 4,146,489, column 1, lines 51-62.

[0007] Grafted polyolefins for use as lubricating oil additives havebeen prepared by dissolving the selected polyolefin in a solvent (whichmay be a lubricating oil base stock), adding an organic peroxide as afree radical generator (also referred to herein as an initiator),holding the mixture at an elevated temperature to form active sites onthe polyolefin, adding the graftable monomer, and allowing the mixtureto react at an elevated temperature for long enough to form the desiredgrafted polyolefin. U.S. Pat. No. 4,092,255, column 4, line 54, tocolumn 5, line 12.

[0008] The prior art also suggests that the grafting reaction to form adispersant VII grafted polyolefin can be controlled to avoid by-productsby combining the polyolefin, graftable monomer, and initiator at atemperature below the initiation (reaction) temperature of theinitiator, then heating the mixture to above that initiation (reaction)temperature to begin the reaction. U.S. Pat. No. 4,146,489. Example 1 ofthe '489 patent suggests that the initiation (reaction) temperature ofdi-t-butyl peroxide is between 160° C. and 170° C. Addition of theinitiator in two stages is suggested in Example 4 of the same patent. Agrafted polyolefin containing 1-10% by weight, preferably 2-6% byweight, most preferably about 3% by weight of the grafted monomer istaught. '489 patent, column 3, lines 11-15.

[0009] U.S. Pat. No. 5,523,008 describes a grafted polyolefin containingat least about 13 moles of N-vinylimidazole or otherethylenically-unsaturated nitrogen-containing and/or oxygen-containingmonomers per mole of a grafted polyolefin backbone. Also described is alubricating oil comprising a lubricant base oil and a grafted polyolefinas described above. Also described is a method of making adispersant-viscosity index improver. N-vinylimidazole or otherethylenically unsaturated nitrogen-containing and/or oxygen-containingmonomers and a graftable polyolefin are reacted with enough of aninitiator to graft at least about 13 moles of the monomer to each moleof the polyolefin.

[0010] U.S. Pat. No. 5,663,126 describes a grafted polyolefin containingone or more of N-vinylimidazole, 4-vinylpyridine, and otherethylenically-unsaturated nitrogen-containing and/or oxygen-containinggraftable monomers grafted to a polyolefin copolymer. Also described isa lubricating oil comprising a lubricant base oil and a graftedpolyolefin as described above. Also described is a method of making adispersant viscosity index improver. N-vinyl-imidazole or otherethylenically unsaturated nitrogen-containing and/or oxygen-containinggraftable monomers and a graftable polyolefin are reacted with enough ofan initiator to graft the monomer to the polyolefin. The initiatorand/or graftable monomer is added to the other ingredients, maintainedat the reaction temperature, over a period of time. The reactiontemperature is maintained at a level high enough to give acceptablereaction times. The monomer and the initiator each can be added at auniform, relatively slow rate during the reaction. Also described is amethod of making a dispersant viscosity index improver using meltreaction conditions. U.S. Pat. Nos. 5,814,586, 5,874,389, and 6,300,289claim priority through one or more continuations of the application thatissued as U.S. Pat. No. 5,663,126 and accordingly have the samedisclosure.

[0011] Other patents disclose the preparation of dispersant viscosityindex improvers by reacting a polyolefin with an acylating agent, andthereafter reacting with an amine so as to form a copolymer havingnitrogenous moieties. For example, U.S. Pat. No. 4,320,019 describesreaction products prepared by reacting (a) interpolymers of ethylene,one or more C₃-C₈ alpha-monoolefins, and one or more polyenes selectedfrom non-conjugated dienes and trienes, with (b) one or more ethyleniccarboxylic acid acylating agents to form an acylating reactionintermediate which is further reacted with (c) an amine. These reactionproducts are said to be useful as multi-functional additives to avariety of lubricating oils for enhancing their dispersancy as well asimproving their viscosity-temperature relationship.

[0012] U.S. Pat. No. 5,424,367 describes a process for carrying outmultiple sequential reactions in a single reactor. A polymer melt isreacted with a first set of reagents to form a grafted functionalcompound, and thereafter the polymer melt is reacted with a second anddifferent set of reagents to include functionalities that are desired inthe final product. The first set of reagents may be unsaturated mono- orpoly-carboxylic acids and cyclic anhydrides, salts, esters, imides,amides, nitrites, and other substituted derivatives from said acids. Apreferred grafted functional compound is maleic anhydride. The secondset of reagents may include alcohols, thioalcohols, and amines, withamines being preferred. Suitable amines include primary amines,N-arylphenylenediamines, aminoperimidines, aminoindoles,aminoindazolinones, and aminomercaptotriazole.

SUMMARY OF THE INVENTION

[0013] The present invention provides novel monomers and methods ofmaking such monomers. Such monomers may be used to prepare DVII's. Oneaspect of the invention is the preparation of a reaction productcomprising one or more ethylenically unsaturated, aliphatic or aromaticmonomers having nitrogen and oxygen atoms. For example, the reactionproduct obtained by reacting maleic anhydride and 4-aminodiphenylamine(“4-ADPA”) contains graftable monomers. This reaction product is amixture and contains, among other components, diphenylaminomaleimide andthe corresponding amic acid. The graftable compounds are then graftedonto the polyolefin using free radical initiators. The graftablecompounds may, but need not, be recovered from the reaction product.

[0014] The term “reaction product” as used in this specification refersto one or more compounds formed by the reaction of two or morereactants. The reaction product may include more than one chemicalcompound formed from the combination of the acylating agent and theamine, and in such instances, the term “reaction product” will beunderstood to refer to all such chemical compounds. The term “monomer”as used in this specification refers to the graftable, ethylenicallyunsaturated, aliphatic or aromatic, nitrogen- and oxygen-containingcompound(s) of the reaction product. The monomer may or may not berecovered from the reaction product before carrying out the graftingreaction. The present methods may also comprise the step of recoveringone or more graftable compounds from the reaction product of theacylating agent and the amine.

[0015] Another aspect of the invention is the graft reaction product ofa polyolefin with an ethylenically unsaturated monomer having nitrogenand oxygen atoms. The present invention also provides polyolefinbackbones grafted with ethylenically unsaturated, aliphatic or aromaticmonomers containing oxygen and nitrogen atoms. It is also contemplatedthat the molar proportions of the grafted monomer to the polyolefin maybe 0.5:1, 1:1, 2:1, 4:1, 8:1, 10:1, 12:1, 15:1, 20:1, 25:1, 40:1, 50:1,or even higher grafted monomer: backbone mole ratios.

[0016] Another aspect of the invention is a method of making adispersant viscosity index improver. According to this invention, agraftable monomer and a polyolefin are provided. In some embodiments thepolyolefin has pendant unsaturated sites for grafting. Sufficientinitiator is provided to graft the graftable monomer to the polyolefin.

[0017] Another aspect of this invention is the grafting of anethylenically-unsaturated, aliphatic or aromatic, nitrogen- andoxygen-containing, graftable monomer to a polyolefin backbone. Thepolyolefin may be reacted so that it contains at least about 1 mole ofmonomer per mole of polymer, though the ratio is not critical for allaspects of the invention. An illustrative monomer is obtained byreacting maleic anhydride and 4-aminodiphenylamine (“4-ADPA”). Thismonomer contains diphenylaminomaleimide and the corresponding amic acid.The monomer is then grafted onto the polyolefin using free radicalinitiators. The monomer may, but need not, be recovered from thereaction product. The polyolefin has a weight average molecular weightof from about 10,000 to about 750,000.

[0018] The polyolefin is dissolved in a solvent, forming a solution. Thegraftable monomer and the initiator are added to the solution. Thegraftable monomer and/or the initiator can be added gradually to thesolution, and they can be added together or successively. The rate ofaddition of the graftable monomer can be from 0.1% to 100% of the entirecharge of monomer per minute. The rate of addition of the initiator canbe from about 0.1% to about 100% of the initiator charge per minute. Thereaction temperature is maintained at a level which gives rise to asatisfactory reaction initiation rate. In one embodiment, the graftablemonomer and the initiator are each added at a uniform, relatively slowrate during the reaction.

[0019] The resulting graft copolymer may have a monomer to polymer ratioof at least about 0.5:1, or alternatively at least about 1:1 oralternatively at least about 2:1 or alternatively at least about 4:1 oralternatively at least about 8:1 or more.

[0020] Additionally, the graft copolymer may be made by melt-blending areaction product according to the present invention; a polyolefin; andan initiator. The reaction is carried out at a temperature and underconditions effective to graft the monomer onto the polyolefin. The graftcopolymer under such circumstances exhibits a monomer to polymer ratioof at least about 0.5:1 or alternatively at least about 1:1 oralternatively at least about 2:1 or alternatively at least about 4:1 oralternatively at least about 8:1 or more.

[0021] Another aspect of the invention is a lubricating oil comprising ahydrocarbon base oil and a graft copolymer as described above. Thepresent invention also provides lubricating oil compositions containingthese graft copolymers in amounts effective to function both asviscosity index improvers and as dispersants.

[0022] The graft copolymer functions as a dispersant viscosity indeximprover, and has the property of raising the viscosity index of thelubricating oil blend by at least about 5 points when used at a 1 wt. %solids concentration in the blend. The dispersant viscosity indeximprover may be used in an amount which is from about 0.05% to 10% byweight of lubricating oil composition.

[0023] As compared with other oil formulations, such lubricating oilsemploy both the dispersancy and the viscosity improving properties ofthe graft copolymer, so less of the oil composition is occupied bydispersants. For example, a 5W-30 lubricating oil can be formulatedwhich employs more of a low-volatility conventional base stock (whichhas a higher viscosity) than previous formulations. This allows theformulator greater latitude to formulate multi-viscosity compositionscontaining less volatiles from the base stock.

[0024] A significant benefit of the present invention is that thereduction in the amount of conventional dispersants improves the wearresistance of the composition in an internal combustion engine ascompared with more conventional formulations.

[0025] The present invention also provides novel methods formanufacturing graft copolymers.

DETAILED DESCRIPTION OF THE INVENTION

[0026] While the invention will be described in connection with one ormore preferred embodiments, it will be understood that the invention isnot limited to those embodiments. On the contrary, the inventionincludes all alternatives, modifications, and equivalents as may beincluded within the spirit and scope of the claims concluding thisspecification.

[0027] Novel monomer according to the present invention are obtained byreacting acylating agents, such as maleic anhydride, with amines, suchas 4-aminodiphenylamine (“4-ADPA”). The novel graft copolymer (alsoreferred to herein as a grafted polyolefin), according to the presentinvention, is made by reacting a polyolefin with the graftable monomerof the present invention, in the presence of an initiator. The reactionmay be carried out either on the solid/molten(melt) polyolefin in anextrusion reactor or on the polymer dissolved in a solvent.

[0028] In the following paragraphs are examples of reactants used in thepreparation of (a) the graftable monomers, (b) grafted polyolefins, and(c) lubricating oil compositions. Also in the following examples areexamples of the initiators, solvents, and optional inhibitorscontemplated for use herein to make the graftable monomers and graftedpolyolefins. Since the materials required to prepare the graftablemonomers and the grafted polyolefins may differ, the components used inthe preparation of the graftable monomer will be discussed separatelyfrom those used in the preparation of the grafted polyolefins. Forexample, the solvent requirements in the preparation of the monomer maydiffer from those needed in the preparation of the grafted polyolefin.As a further example, while limits may be set upon the concentration ofaromatics in the solvent used in the preparation of the graftedpolyolefin, such limits may not be necessary in the preparation of thegraftable monomer. In addition, solvents having a higher degree ofpolarity are preferred in the preparation of the graftable monomer.

[0029] I. Materials and Methods for Preparation of Graftable Monomers

[0030] A. Solvents for use in the Preparation of Graftable Monomers

[0031] Useful solvents include volatile solvents which are readilyremovable from the monomer after the reaction is complete or ones whichare not readily volatilized and removed after completion of thereaction. Any solvent may be used which can disperse or dissolve thereaction product and may be handled in such a way as not to participateappreciably in the reaction or cause side reactions to a material degreeor interfere with subsequent processes which utilize the graftablemonomer. Several examples of solvents of this type include straightchain or branched chain aliphatic or alicyclic hydrocarbons, such asn-pentane, n-heptane, i-heptane, n-octane, i-octane, nonane, decane,cyclohexane, dihydronaphthalene, decahydronaphthalene, and relativelyvolatile aromatics such as toluene, xylene, and ethylbenzene and othersnot listed. Nonreactive halogenated aromatic hydrocarbons such aschlorobenzene, dichlorobenzene, trichlorobenzene, dichlorotoluene andothers are also useful as solvents. Aliphatic or aromatic ketones,ethers, esters, formamides, carbonates, water etc., are alsocontemplated as solvents herein. Also contemplated are mixtures ofsolvents.

[0032] Examples of the ketones, ethers, esters, formamides, carbonates,etc. which are contemplated include, but are not limited to, acetone,methylethyl ketone, diethyl ketone, N,N-dimethylformamide,N,N-diethylformamide, N,N-dimethylacetamide, diethyl carbonate,propylene carbonate, diethyl ether, dimethyl ether, isopropyl ether,2-methoxyethyl ether, dioxane, dimethyl sulfoxide, butyl acetate, ethylacetate, and dimethyl malonate.

[0033] The solvents useful here also include base oils or base stocks,as defined in ASTM D 6074-99, “Standard Guide for CharacterizingHydrocarbon Lubricant Base Oils” which may be suitable for incorporationinto a final lubricating oil product. In this specification, the termbase oil includes base oils and base stocks. Any base oil may be usedwhich can disperse or dissolve the reaction product without materiallyparticipating in the reaction or causing side reactions to anunacceptable degree. For example, solvent dewaxed and hydrocracked baseoils, paraffin and isoparaffin fluids, base oils which contain low ormoderate levels of aromatic constituents, and fluid poly-α-olefins arecontemplated for use herein. The use of base oils having aromaticconstituents, while being less than optimum in some instances, iscontemplated under this disclosure.

[0034] For example, suitable base oils of this kind include, but are notlimited to 100 SUS, 130 SUS, or 150 SUS low pour solvent neutral baseoils, sold as lubricant base oils by ExxonMobil Corporation. Also baseoils marketed by PetroCanada, of Calgary, including HT 60, HT 70, HT100, and HT 160, are also contemplated. These are fluids having about0.2% aromatic constituents.

[0035] B. Acylating Agents for use in the Preparation of GraftableMonomers

[0036] In this specification, the terms olefinic unsaturation andethylenic unsaturation are used interchangeably. The acylating agent hasat least one point of olefinic unsaturation (in other words, C═C) in itsstructure. Usually, the point of olefinic unsaturation will correspondto —HC═CH— or —HC═CH₂. Acylating agents where the point of olefinicunsaturation is α, β to a carboxy functional group are very useful.Olefinically unsaturated mono-, di-, and polycarboxylic acids, the loweralkyl esters thereof, the halides thereof, and the anhydrides thereofrepresent typical acylating agents in accordance with the presentinvention. Preferably, the olefinically unsaturated acylating agent is amono- or dibasic acid, or a derivative thereof such as anhydrides, loweralkyl esters, halides and mixtures of two or more such derivatives.“Lower alkyl” means alkyl groups of one to seven carbon atoms.

[0037] The acylating agent may include at least one member selected fromthe group consisting of monounsaturated C₄ to C₅₀, alternatively C₄ toC₂₀, alternatively C₄ to C₁₀, dicarboxylic acids monounsaturated C₃ toC₅₀, alternatively C₃ to C₂₀, alternatively C₃ to C₁₀, monocarboxylicacids and anhydrides thereof (that is, anhydrides of those carboxylicacids or of those monocarboxylic acids), and combinations of any of theforegoing (that is, two or more of those acids and/or anhydrides).

[0038] Suitable acylating agents include acrylic acid, crotonic acid,methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconicacid, itaconic anhydride, citraconic acid, citraconic anhydride,mesaconic acid, glutaconic acid, chloromaleic acid, aconitic acid,methylcrotonic acid, sorbic acid, 3-hexenoic acid, 10-decenoic acid,2-pentene-1,3,5-tricarboxylic acid, cinnamic acid, and lower alkyl(e.g., C₁ to C₄ alkyl) acid esters of the foregoing, e.g., methylmaleate, ethyl fumarate, methyl fumarate, etc. Particularly preferredare the unsaturated dicarboxylic acids and their derivatives; especiallymaleic acid, fumaric acid and maleic anhydride.

[0039] C. Amines for use in the Preparation of Graftable Monomers

[0040] The amines must be capable of being acylated by the appropriateacylating agent, namely primary or secondary amines. Amines capable ofbeing acylated are disclosed in U.S. Pat. No. 4,320,019, column 4, line60 to column 6, line 14; U.S. Pat. No. 5,424,367, column 10, line 61 tocolumn 13, line 18; U.S. Pat. No. 5,427,702, column 13, line 5 to column17, line 32. Each of these disclosures is hereby incorporated byreference herein.

[0041] Among the various amine types useful in the practice of thisinvention are alkylene amines, alkylene polyamines, aromatic amines, andpolyoxyalkylene polyamines.

[0042] Some examples of the alkylene amines and alkylene polyaminesinclude methyleneamines, ethyleneamines, butyleneamines,propyleneamines, pentyleneamines, hexyleneamines, heptyleneamines,octyleneamines, other polymethyleneamines, the cyclic and higherhomologs of these amines such as the piperazines, theamino-alkyl-substituted piperazines, etc. These amines include, forexample, ethylene diamine, diethylene triamine, triethylene tetramine,propylene diamine, di(heptamethylene)triamine, tripropylene tetramine,tetraethylene pentamine, trimethylene diamine, pentaethylene hexamine,di(trimethylene)triamine, as well as other polyaminic materials. Otherhigher homologs obtained by condensing two or more of theabove-mentioned alkyleneamines may be used.

[0043] Examples of suitable polyoxyalkylene polyamines are those whichhave the formulae.

[0044] (i) NH₂(-alkylene-O-alkylene)_(m)NH₂

[0045] where m has a value of about 3 to 70 and preferably 10 to 35; and

[0046] (ii) R-(alkylene(-O-alkylene)_(n)NH₂)₃₋₆

[0047] where n has a value of about 1 to 40 with the provision that thesum of all the n's is from about 3 to about 70 and preferably from about6 to about 35 and R is a polyvalent saturated hydrocarbon radical of upto ten carbon atoms. The alkylene groups in either formula (i) or (ii)may be straight or branched chains containing about 2 to 7, andpreferably about 2 to 4 carbon atoms.

[0048] The polyoxyalkylene polyamines, such as polyoxyalkylene diaminesand polyoxyalkylene triamines, may have average molecular weightsranging from about 200 to about 4000 and preferably from about 400 toabout 2000. Suitable polyoxyalkylene polyamines include thepolyoxyethylene and polyoxypropylene diamines and the polyoxypropylenetriamines having average molecular weights ranging from about 200 to2000.

[0049] Other amine types useful in the practice of this inventioninclude amino-aromatic compounds such as N-arylphenylenediaminesrepresented by the formula:

[0050] in which Ar is aromatic and R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a branched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical can be an alkyl,alkenyl, alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkylradical, R₂ is —NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, CH₂—(CH₂)_(n)—NH₂,--aryl--NH₂, in which n and m has a value from 1 to 10, and R₃ ishydrogen or an alkyl, alkenyl, alkoxyl, arylalkyl, or alkylaryl radical,which may have from 4 to 24 carbon atoms.

[0051] Suitable N-arylphenylenediamine compounds may also be representedby the formula:

[0052] in which R₄, R₅ and R₆ are hydrogen or a linear or branchedhydrocarbon radical containing from 1 to 10 carbon atoms and thatradical may be an alkyl, alkenyl, alkoxyl, alkylaryl, arylalkyl,hydroxyalkyl, or aminoalkyl radical, and R₄, R₅ and R₆ can be the sameor different.

[0053] Particularly preferred N-arylphenylenediamines are theN-phenylphenylenediamines, for example, N-phenyl-1,4-phenylenediamine(also referred to herein as 4-aminodiphenylamine),N-phenyl-1,3-phenylenediamine, N-phenyl-1,2-phenylenediamine,N-naphthyl-phenylenediamine, N-phenylnaphthalenediamine andN′-aminopropyl-N-phenylphenylenediamine. Most preferably, the amine is4-aminodiphenylamine (also called N-phenyl-1,4-phenylenediamine).

[0054] Other useful amine types include aminocarbazoles such as thoserepresented by the formula:

[0055] in which R₇ and R₈ represent hydrogen or an alkyl, alkenyl, oralkoxyl radical having from 1 to 14 carbon atoms, and R₇ and R₈ can bethe same or different;

[0056] aminoindoles such as those represented by the formula:

[0057] in which R₉ represents hydrogen or an alkyl radical having from 1to 14 carbon atoms,

[0058] amino-indazolinones such as those represented by the formula:

[0059] in which R₁₀ is hydrogen or an alkyl radical having from 1 to 14carbon atoms,

[0060] aminomercaptotriazole as represented by the formula:

[0061] aminoperimidines such as those represented by the formula:

[0062] in which R₁₁ represents hydrogen or an alkyl or alkoxyl radicalhaving from 1 to 14 carbon atoms.

[0063] Other useful amines include:2-heptyl-3-(2-aminopropyl)imidazoline, 4-methylimidazoline,1,3-bis-(2-aminoethyl)imidazoline, (2-aminopropyl)-piperazine,1,4-bis-(2-aminoethyl)piperazine, N,N-dimethyaminopropyl amine,N,N-dioctylethyl amine, N-octyl-N′-methylethylene diamine, and2-methyl-1-(2-aminobutyl) piperazine, and aminothiazoles from the groupconsisting of aminothiazole, aminobenzothiazole, aminobenzothiadiazoleand aminoalkylthiazole.

[0064] It is also contemplated that combinations of the above amines maybe used to react with one or more acylating agents.

[0065] The choice of amine compound will depend, in part, upon thenature of the acylating agent. In the case of the preferred acylatingagent, maleic anhydride, those that will react advantageously with theanhydride functionality are most preferred and, therefore, appropriate.Primary amines are preferred because of the stability of the imideproducts formed. Primary amines, structurally described as RNH₂, may beused in which the R group may contain performance enhancingfunctionalities desirable for the final product. Such properties mayinclude, among others, wear protection, friction reduction andprotection against oxidation. Incorporation of elements in addition tocarbon, hydrogen and nitrogen, such as, but not limited to, the halogensor sulfur or oxygen, either alone or in combination, is alsocontemplated.

[0066] D. Method of Preparation of Graftable Monomers

[0067] A novel method is provided herein of making an ethylenicallyunsaturated, aliphatic or aromatic, nitrogen- and oxygen-containing,graftable monomer, suitable for grafting to a polyolefin to form adispersant viscosity index improver. The method comprises the step offorming an acylating agent mixture comprising a solvent and an acylatingagent having at least one point of olefinic unsaturation. The acylatingagent may be dissolved or dispersed in the solvent, and the acylatingagent mixture may be a solution or a dispersion. Suitable solventsinclude oxygenates such as acetone, base oils, and amides such asN,N-dimethyl formamide. The method also comprises the step of adding anamine to the acylating agent mixture, thereby forming a mixture. Theamine may be added to the acylating agent all at once or slowly, forexample, by adding aliquots or metering over a period of time.“Metering” means to add, by drops or continuously, a specific amountover a certain time. The method may comprise the simultaneous meteringof the acylating agent and the amine into the solvent or premixing theacylating agent and the amine prior to mixing the reactants withsolvent. The method also comprises the step of heating the mixture. Theacylating agent and/or the amine may be heated before, during or afterthey are combined. The method forms a reaction product of the acylatingagent and the amine. The monomer may or may not be recovered from thereaction product before carrying out the grafting reaction. The presentmethods may also comprise the step of recovering one or more graftablecomponents from the reaction product of the acylating agent and theamine.

[0068] The acylating agent and the amine may be provided in suitableweight ratios, though such ratios are not critical for all aspects ofthe invention. Suitable weight ratios of amine to acylating agentinclude, but are not limited to, the ranges of from about 0.1:1 to about2:1, from about 0.1:1 to about 6:1, from about 0.2:1 to about 6:1, fromabout 0.3:1 or 0.6:1 to about 2:1, and from about 1:1 to about 4:1.Where the acylating agent is maleic acid, preferred weight ratios are inthe range of from about 0.6:1 to about 2:1. Where the acylating agent ismaleic anhydride, preferred weight ratios are in the range of from about0.3:1 to about 2:1.

[0069] II. Materials and Methods for Preparation of Graft Copolymers

[0070] A. Polyolefins for use in the Preparation of Graft Copolymers

[0071] A wide variety of polyolefins (which may or may not have pendantunsaturation) are contemplated for use as a backbone for graffing.Examples of polyolefins contemplated for use include olefinhomopolymers, copolymers, and terpolymers, such as, but not limited to,polyethylene, polypropylene, ethylene-propylene copolymers, polymerscontaining two or more monomers, polyisobutene, polymethacrylates,polyalkylstyrenes, partially hydrogenated polyolefins of butadiene andstyrene and copolymers of isoprene, such as polymers of styrene andisoprene. EPDM (ethylene/propylene/diene monomer) polymers,ethylene-propylene octene terpolymers and ethylene-propylene ENBterpolymers, are also contemplated for use.

[0072] Materials contemplated for use herein includeethylene/propylene/diene polyolefins containing from about 15% to about90% ethylene and from about 10% to about 85% propylene moieties bynumber, or alternatively, from 30% to about 75% ethylene and from about25% to about 70% propylene moieties by number. These materials may beoptionally modified with from 0% to about 9% diene monomers. Usefuldiene monomers include 1,4-hexadiene, dicyclopentadiene,2,5-norbornadiene, 5-ethylidene-2-norbornene, and1-allyl-4-isopropylidene cyclohexane and combinations of two or morediene monomers. Polyolefins contemplated for use include by referencethose suggested in U.S. Pat. Nos. 4,092,255, 4,640,788, 5,219,480,5,298,565 and 6,410,652. The polyolefins contemplated herein may haveweight average molecular weights of from about 10,000, alternativelyfrom about 20,000 to about 500,000.

[0073] Specific materials which are contemplated for use herein includeolefin copolymers of principally ethylene, and propylene withtermonomers such as, but not limited to, octene and ENB marketed byDuPont Dow Elastomers, Wilmington, Del.; VISNEX polyolefins, comprisedof ethylene, propylene, and ENB sold by Mitsui Petrochemical Industries,Ltd., Tokyo, Japan; VISTALON ethylene-propylene polyolefins, sold byExxonMobil Chemical, Houston, Tex.; also the family of PARATONEpolyolefins comprised primarily of ethylene and propylene, marketed byChevron Oronite Company, L.L.C., headquartered in Houston, Tex.;styrene/butadiene, hydrogenated isoprene copolymers and styrene/isoprenemarketed by Infineum International, Ltd.., Abingdon, UK or Infineum USALP, Linden, N.J., such as SV-50, SV-200, SV-250 and SV-300 also olefincopolymers based on ethylene and propylene marketed by InfineumInternational, Ltd.., Abingdon, UK or Infineum USA LP, Linden, N.J.;elastomers available from DSM Copolymer are also contemplated, as arepolymers marketed under the DUTRAL name by Polimeri Europa, of Ferrara,Italy such as CO-029, CO-034, CO-043, CO-058, TER 4028 and TER 4044. TheUniroyal line of polymers marketed by Crompton Corporation ofMiddlebury, Conn. under the ROYALENE name such as 400, 501, 505, 525,535, 563 and 580 HT are also contemplated. Combinations of the abovematerials, and other, similar materials, are also contemplated.

[0074] B. Initiators for use in the Preparation of Graft Copolymers

[0075] Broadly, any free-radical initiator capable of operating underthe conditions of the reactions as outlined in the present specificationis contemplated for use herein. Representative initiators are disclosedin U.S. Pat. No. 4,146,489, column 4, lines 45-53, which is incorporatedhere by reference. Specific “peroxy” initiators contemplated hereininclude alkyl, dialkyl, and aryl peroxides, for example: di-t-butylperoxide (abbreviated herein as “DTBP”), dicumyl peroxide, t-butyl cumylperoxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane,and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3. Also contemplated areperoxyester and peroxyketal initiators, for example: t-butylperoxybenzoate, t-amylperoxy benzoate, t-butylperoxy acetate, t-butylperoxybenzoate, di-t-butyl diperoxyphthalate, and t-butylperoxy isobutyrate.Also contemplated are hydroperoxides, for example: cumene hydroperoxide,t-butyl hydroperoxide, and hydrogen peroxide. Also contemplated are azoinitiators, for example: 2-t-butylazo-2-cyanopropane,2-t-butylazo-1-cyanocyclohexane, 2,2′-azobis(2,4-dimethylpentanenitrile), 2,2′-azobis(2-methylpropane nitrile),1,1′-azobis(cyclohexanecarbonitrile), and azoisobutyronitrile (AIBN).Other similar materials are also contemplated such as, but not limitedto, diacyl peroxides, ketone peroxides and peroxydicarbonates. It isalso contemplated that combinations of more than one initiator,including combinations of different types of initiators, may beemployed.

[0076] Each such initiator commonly has a characteristic minimumreaction initiation temperature, above which it will readily initiate areaction and below which the reaction will proceed more slowly or not atall. Consequently, the minimum reaction temperature is commonly dictatedby the selected initiator.

[0077] C. Solvents for use in the Preparation of Graft Copolymers

[0078] Useful solvents include volatile solvents which are readilyremovable from the grafted polyolefin after the reaction is complete orones which are not readily volatilized and removed after completion ofthe reaction. Any solvent may be used which can disperse or dissolve thecomponents of the reaction mixture which include monomer, monomercomponents or precursors and polyolefin and which will not participateappreciably in the reaction or cause side reactions to a materialdegree. Several examples of solvents of this type include straight chainor branched aliphatic or alicyclic hydrocarbons, such as n-pentane,n-heptane, i-heptane, n-octane, i-octane, nonane, decane, cyclohexane,dihydronaphthalene, decahydronaphthalene and others. Aliphatic ketones,ethers, esters, etc., which are suitable for dissolving or dispersingthe polymer are also contemplated as solvents herein. Nonreactivehalogenated aromatic hydrocarbons such as chlorobenzene,dichlorobenzene, trichlorobenzene, dichlorotoluene and others are alsouseful as solvents. Also contemplated are mixtures of solvents.

[0079] The solvents useful here also include base oils which may besuitable for incorporation into a final lubricating oil product. Anybase oil may be used which can disperse or dissolve the reactantswithout materially participating in the reaction or causing sidereactions to an unacceptable degree. For example, solvent dewaxed andhydrocracked base oils, paraffin and isoparaffin fluids, base oils whichcontain low or moderate levels of aromatic constituents, and fluidpoly-α-olefins are contemplated for use herein. The use of base stockshaving aromatic constituents, while being less than optimum in someinstances, is contemplated under this disclosure.

[0080] In this specification, the “level of aromatic constituents” isdefined as the weight percentage of molecular species containingaromatic carbon atoms. The petroleum oil solvents contemplated here arethose containing less than about 50% by weight of molecular aromaticimpurities, alternatively less than about 30% by weight of moleculararomatic impurities, alternatively less than about 20% by weight of suchimpurities, alternatively less than about 15% by weight of suchimpurities, alternatively less than about 10% by weight of suchimpurities, alternatively less than about 5% by weight of suchimpurities, alternatively less than about 1% of such impurities,alternatively about 0.3% or less of such impurities.

[0081] Examples of suitable solvent base oils are as follows.

[0082] The higher aromatic fluids contemplated for the present use havearomatic contents of from about 15 wt % to about 35 wt %. Suitable oilsof this kind include, for example, 100 SUS, 130 SUS, or 150 SUS low poursolvent neutral base oils, sold as lubricant base oils by ExxonMobilCorporation.

[0083] Fluids having intermediate concentrations of aromatics for use inthe present application include ones ranging from about 10 wt % to 15 wt% aromatics. Contemplated for use as fluids with intermediateconcentrations of aromatics are blends of fluids having high and lowaromatics concentrations as well as directly manufactured fluids havingintermediate concentrations of aromatics.

[0084] Base oils with somewhat lower concentrations of aromaticscontemplated for the present use include the following materials:CHEVRON NEUTRAL OIL 100R, sold by ChevronTexaco; moderately higharomatic content oils such as naphthenic oil, for which the aromaticcontent is about 5-12 wt %; blends of any of the individual oils namedin this specification; and others.

[0085] The minimally aromatic fluids contemplated for use in the presentcontext include hydrotreated oils having from about 0.1 to about 5 wt %aromatic content. Representative minimally aromatic fluids includePetroCanada HT 60 (P 60 N), HT 70 (P 70 N), HT 100 (P 100 N), and HT 160(P 160 N) straight cut or blended oil stocks having about 0.2% aromaticconstituents, sold for use in lubricating oils by PetroCanada, Calgary,Alberta; RLOP (derived from “Richmond Lube Oil Plant”) 100 N or 240 Nstraight or blended low aromatic content hydrotreated oil stocks,containing about 0.5% aromatic constituents, sold by ChevronTexaco; andlow aromatic content stocks marketed by both ExxonMobil Corporation ofFairfax, Va. and Motiva Enterprises LLC. In general, Group I, Group II,Group III, Group IV and Group V base stock categories are contemplatedfor use.

[0086] Aromatic-free process fluids can also be used to carry out thepresent invention. Several examples of process fluids containing nomeasurable aromatic constituents include synthetic poly-alpha-olefin(“PAO”) base stocks and highly refined paraffinic and isoparaffinicfluids.

[0087] The preferable range of aromatic content in the process fluid isabout 0-15 wt %, alternatively about 0-10 wt %. The most preferablerange is about 0-5 wt %.

[0088] D. Inhibitors

[0089] Inhibitors may optionally be used in the present graftingreaction to limit the degree of crosslinking of the polyolefin. Theinventors contemplate that limiting the amount of crosslinking willreduce the viscosity increase resulting from the grafting reaction andprovide a final grafted polyolefin which has improved shear stability.

[0090] One category of inhibitors contemplated herein is that ofhindered phenols, which are commonly used as antioxidants or freeradical inhibitors. One representative hindered phenol for this purposeis octadecyl-3,5-di-t-butyl-4-hydroxyhydrocinnamate. Anotherrepresentative inhibitor is hydroquinone.

[0091] E. Solution Reaction Methods for Preparation of Graft Copolymer

[0092] The present reaction can be carried out as follows. Thepolyolefin to be grafted is first dissolved in a process fluid at apolymer solids concentration ranging from about 1% to about 25%, forexample, about 12.5%. In order to dissolve the polyolefin, thepolyolefin is granulated and then dissolved in an appropriate reactionsolvent. This solvent may be a typical lubricant base oil or any othersuitable solvent. This dissolution step is generally carried out underan inert gas blanket, or with an inert gas purge, at a temperature lowerthan the reaction temperature. Typically dissolution is carried out attemperatures from 60° C. to about 120° C., for example, about 100° C.The dissolution temperature will normally be less than the reactiontemperature. Holding the mixture at a higher temperature may degrade thecomponents. Both the initiator and the monomer may also be blended withappropriate solvents. The initiator concentration, in its blend, rangesfrom about 1 wt % to 100 wt % and the monomer concentration, in itsblend, also ranges from about 1 wt % to 100 wt %. For example, theinitiator and monomer blend concentrations may be 3 wt % and 30 wt %respectively.

[0093] The polymer solution is transferred to a suitable reactor whichcan be purged or blanketed with an inert gas for example, nitrogen,carbon dioxide, helium, or argon or otherwise isolated from ambientoxygen gas as required. A heated batch reactor is suitable.

[0094] The polyolefin solution is heated to the desired reactiontemperature, chosen so that essentially all of the initiator is consumedduring the time allotted for the reaction. For example, if DTBP(di-t-butyl peroxide) is used as the initiator, the reaction temperatureshould be greater than about 160° C., alternatively greater than about165° C., alternatively greater than about 170° C., alternatively greaterthan about 175° C., alternatively about 170° C., alternatively about175° C., alternatively less than about 175° C., alternatively less thanabout 180° C., alternatively less than about 185° C., alternatively lessthan about 190° C., alternatively less than about 195° C., alternativelyless than about 200° C.

[0095] Since the various acceptable initiators have different optimumreaction temperatures, the choice of a particular initiator may requireadjustment of the reaction temperature or the reaction time in orderthat the reaction conditions be compatible with the choice of initiator.

[0096] 1. Molar Proportion of Monomer

[0097] The contemplated proportions of the graftable monomer to thepolyolefin and reaction conditions are selected so that an effectivepercentage (ideally, most or all of the reactant charge) of thegraftable monomer will graft directly onto the polyolefin, rather thanforming dimeric, oligomeric, or homopolymeric graft moieties or entirelyindependent homopolymers. The alternatively contemplated minimum moleratios of the graftable monomer to the starting polyolefin are asfollows:

[0098] at least about 1 mole,

[0099] alternatively at least about 2 moles,

[0100] alternatively at least about 3 moles,

[0101] alternatively at least about 4 moles,

[0102] alternatively at least about 5 moles,

[0103] alternatively at least about 6 moles,

[0104] alternatively at least about 7 moles,

[0105] alternatively at least about 8 moles,

[0106] alternatively at least about 9 moles,

[0107] alternatively at least about 10 moles,

[0108] alternatively at least about 11 moles,

[0109] alternatively at least about 12 moles,

[0110] alternatively at least about 13 moles,

[0111] alternatively at least about 14 moles,

[0112] alternatively at least about 15 moles,

[0113] alternatively at least about 16 moles,

[0114] alternatively at least about 17 moles,

[0115] alternatively at least about 18 moles,

[0116] alternatively at least about 19 moles,

[0117] alternatively at least about 20 moles,

[0118] alternatively at least about 22 moles,

[0119] alternatively at least about 24 moles,

[0120] alternatively at least about 26 moles,

[0121] alternatively at least about 28 moles,

[0122] alternatively at least about 30 moles,

[0123] alternatively at least about 40 moles,

[0124] alternatively at least about 50 moles,

[0125] alternatively at least about 60 moles,

[0126] alternatively at least about 70 moles,

[0127] alternatively at least about 80 moles,

[0128] alternatively at least about 100 moles,

[0129] alternatively at least about 120 moles,

[0130] of the graftable monomer per mole of the starting polyolefin. Thecontemplated maximum molar proportions of the graftable monomer to thestarting polyolefin are as follows:

[0131] at most about 20 moles,

[0132] alternatively at most about 22 moles,

[0133] alternatively at most about 24 moles,

[0134] alternatively at most about 26 moles,

[0135] alternatively at most about 28 moles,

[0136] alternatively at most about 30 moles,

[0137] alternatively at most about 40 moles,

[0138] alternatively at most about 50 moles,

[0139] alternatively at most about 60 moles,

[0140] alternatively at most about 70 moles,

[0141] alternatively at most about 80 moles,

[0142] alternatively at most about 100 moles,

[0143] alternatively at most about 110 moles,

[0144] alternatively at most about 120 moles,

[0145] or more of the graftable monomer per mole of the startingpolyolefin.

[0146] A contemplated maximum molar proportion of the graftable monomerto the starting polyolefin may be desirable in several situations. Forexample, it may be preferable to select a contemplated maximum molarproportion of the graftable monomer to the starting polyolefin in orderto facilitate manufacturing control product quality. For example, molarproportions in excess of about 25:1, may result in the formation ofinsolubles or gels which may, under certain conditions, slowmanufacturing and impair product quality. Thus, it may be preferable toemploy a contemplated maximum molar ratio of the graftable monomer tothe starting polyolefin of at most about 20 moles, alternatively at mostabout 22 moles, alternatively at most about 24 moles, alternatively atmost about 25 mole (when it is expected that 100% of the monomer graftsto the polymer). One of ordinary skill in the art will recognize thathigher maximum molar proportions may be desirable when othercircumstances are involved. For example, to generate efficaciousproduct, it may be desirable to prepare a graft reaction product havinga molar proportion of grafted monomer to the polymer of at most about30:1, alternatively at most about 40:1 or another suitable maximumdisclosed herein.

[0147] The graftable monomer may be introduced into the reactor all atonce, in several discrete charges, or at a steady rate over an extendedperiod. The desired minimum rate of addition of the graftable monomer tothe reaction mixture is selected from:

[0148] at least about 0.1%,

[0149] alternatively at least about 0.5%,

[0150] alternatively at least about 1.0%,

[0151] alternatively at least about 1.2%,

[0152] alternatively at least about 1.4%,

[0153] alternatively at least about 1.6%,

[0154] alternatively at least about 1.8%,

[0155] alternatively at least about 2.0%,

[0156] alternatively at least about 2.2%,

[0157] alternatively at least about 2.4%,

[0158] alternatively at least about 2.6%,

[0159] alternatively at least about 2.8%,

[0160] alternatively at least about 3.0%,

[0161] alternatively at least about 3.2%,

[0162] alternatively at least about 3.4%,

[0163] alternatively at least about 3.6%,

[0164] alternatively at least about 3.8%,

[0165] alternatively at least about 4.0%,

[0166] alternatively at least about 4.5%,

[0167] alternatively at least about 5.0%,

[0168] alternatively at least about 20%,

[0169] alternatively at least about 50%,

[0170] alternatively at least about 100%,

[0171] of the necessary charge of graftable monomer per minute. Whenadded over time, the monomer can be added at an essentially constantrate, or at a rate which varies with time. Any of the above values canrepresent an average rate of addition or the minimum value of a ratewhich varies with time.

[0172] The desired maximum rate of addition is selected from:

[0173] at most about 0.1%,

[0174] alternatively at most about 0.5%,

[0175] alternatively at most about 1.0%,

[0176] alternatively at most about 1.2%,

[0177] alternatively at most about 1.4%,

[0178] alternatively at most about 1.6%,

[0179] alternatively at most about 1.8%,

[0180] alternatively at most about 2.0%,

[0181] alternatively at most about 2.2%,

[0182] alternatively at most about 2.4%,

[0183] alternatively at most about 2.6%,

[0184] alternatively at most about 2.8%,

[0185] alternatively at most about 3.0%,

[0186] alternatively at most about 3.2%,

[0187] alternatively at most about 3.4%,

[0188] alternatively at most about 3.6%,

[0189] alternatively at most about 3.8%,

[0190] alternatively at most about 4.0%,

[0191] alternatively at most about 4.5%,

[0192] alternatively at most about 5.0%,

[0193] alternatively at most about 20%,

[0194] alternatively at most about 100%

[0195] of the necessary charge of graftable monomer per minute. Any ofthe above values can represent an average rate of addition or themaximum value of a rate which varies with time.

[0196] The graftable monomer may be added as a neat liquid, in solid ormolten form, or cut back with a solvent. While it may be introducedneat, it is preferably cut back with a solvent to avoid high localizedconcentrations of the monomer as it enters the reactor. In a preferredembodiment, it is substantially diluted with the process fluid (reactionsolvent). The monomer can be diluted by at least about 5 times,alternatively at least about 10 times, alternatively at least about 20times, alternatively at least about 50 times, alternatively at leastabout 100 times its weight or volume with a suitable solvent ordispersing medium.

[0197] 2. Molar Proportion of Initiator

[0198] The contemplated proportions of the initiator to the graftablemonomer and the reaction conditions are selected so that at least many,and ideally, all of the monomer will graft directly onto the polyolefin,rather than forming dimeric, oligomeric, or homopolymeric graft moietiesor entirely independent homopolymers. The contemplated minimum molarproportions of the initiator to the graftable monomer are from about0.05:1 to about 2:1. No specific maximum proportion of the initiator iscontemplated, though too much of the initiator may degrade thepolyolefin, cause problems in the finished formulation and increase costand, therefore, should be avoided.

[0199] While the initiator may be added neat, in a preferred embodiment,it is introduced “cut-back” with solvent in order to avoid localizedregions of elevated concentration. The initiator can be added before,with or after the graftable monomer. For example, the initiator may beadded so that, at any given time, the amount of unreacted initiatorpresent is much less than the entire charge, and preferably a smallfraction of the entire charge. In one embodiment, the initiator may beadded after substantially all the graftable monomer has been added, sothere is an excess of both the graftable monomer and the polyolefinduring essentially the entire reaction. In another embodiment, theinitiator may be added along with the graftable monomer, either atessentially the same rate (measured as a percentage of the entire chargeadded per minute) or at a somewhat faster or slower rate, so there is anexcess of polyolefin to unreacted initiator and unreacted monomer. Forthis embodiment, the ratio of unreacted initiator to unreacted monomerremains substantially constant during most of the reaction.

[0200] 3. Rate of Addition of Initiator

[0201] The initiator may be introduced into the reactor in several (or,alternatively, many) discrete charges, or at a steady rate over anextended period. The desired minimum rate of addition of the initiatorto the reaction mixture is selected from:

[0202] at least about 0.1%,

[0203] alternatively at least about 0.5%,

[0204] alternatively at least about 1.0%,

[0205] alternatively at least about 1.2%,

[0206] alternatively at least about 1.4%,

[0207] alternatively at least about 1.6%,

[0208] alternatively at least about 1.8%,

[0209] alternatively at least about 2.0%,

[0210] alternatively at least about 2.2%,

[0211] alternatively at least about 2.4%,

[0212] alternatively at least about 2.6%,

[0213] alternatively at least about 2.8%,

[0214] alternatively at least about 3.0%,

[0215] alternatively at least about 3.2%,

[0216] alternatively at least about 3.4%,

[0217] alternatively at least about 3.6%,

[0218] alternatively at least about 3.8%,

[0219] alternatively at least about 4.0%,

[0220] alternatively at least about 4.5%,

[0221] alternatively at least about 5.0%,

[0222] alternatively at least about 20%

[0223] alternatively at least about 50%,

[0224] alternatively at least about 100%,

[0225] of the necessary charge of initiator per minute. The initiatorcan be added at an essentially constant rate, or at a rate which varieswith time. Any of the above values can represent an average rate ofaddition or the minimum value of a rate which varies with time.

[0226] The desired maximum rate of addition of the initiator to thereaction mixture is selected from:

[0227] at most about 0.1%,

[0228] alternatively at most about 0.5%,

[0229] alternatively at most about 1.0%,

[0230] alternatively at most about 1.2%,

[0231] alternatively at most about 1.4%,

[0232] alternatively at most about 1.6%,

[0233] alternatively at most about 1.8%,

[0234] alternatively at most about 2.0%,

[0235] alternatively at most about 2.2%,

[0236] alternatively at most about 2.4%,

[0237] alternatively at most about 2.6%,

[0238] alternatively at most about 2.8%,

[0239] alternatively at most about 3.0%,

[0240] alternatively at most about 3.2%,

[0241] alternatively at most about 3.4%,

[0242] alternatively at most about 3.6%,

[0243] alternatively at most about 3.8%,

[0244] alternatively at most about 4.0%,

[0245] alternatively at most about 4.5%,

[0246] alternatively at most about 5.0%,

[0247] alternatively at most about 10%,

[0248] alternatively at most about 20%,

[0249] alternatively at most about 40%,

[0250] alternatively at most about 50%,

[0251] alternatively at most about 100%

[0252] of the necessary charge of initiator per minute. Any of the abovevalues can represent an average rate of addition or the maximum value ofa rate which varies with time.

[0253] While the initiator can be added neat, it is preferably cut backwith a solvent to avoid high localized concentrations of the initiatoras it enters the reactor. In a preferred embodiment, it is substantiallydiluted with the process fluid (reaction solvent). The initiator can bediluted by at least about 5 times, alternatively at least about 10times, alternatively at least about 20 times, alternatively at leastabout 50 times, alternatively at least about 100 times its weight orvolume with a suitable solvent or dispersing medium.

[0254] If a polymerization inhibitor is to be used, the inventorscontemplate that it may be added after the other ingredients have beenadded. The inhibitor may constitute from 0 to about 1 weight percent ofthe reaction mixture, alternatively from about 0.01 wt % to about 0.5 wt% of the reaction mixture, alternatively 0.05 wt % to 0.10 wt % of thereaction mixture. It may be added immediately, after the other reactantsor after a time delay. The inhibitor may be added all at once or over atime interval.

[0255] 4. Procedure for Grafting Reactor

[0256] After the reactants and the inhibitor (if any) have been added,the reaction mixture is preferably mixed with heating for an additional2 to 120 minutes to complete the reaction. The time required forcompletion of the reaction can be determined experimentally, bydetermining when the proportion of nitrogen, or of the grafted monomerin solution, reaches a value at or approaching a minimum pre-establishedvalue, or when the viscosity approaches a near constant value.

[0257] After the reaction has gone essentially to completion, the heatcan be removed and the reaction product can be allowed to cool in thereactor with mixing. Alternatively, more aggressive cooling can beemployed, using a heat exchanger or other apparatus. Alternatively, thereaction product may be removed while still at or near reactiontemperature.

[0258] F. Melt Reaction Conditions for Preparation of Graft Polyolefin

[0259] Alternatively, the grafting reaction can be carried out underpolymer melt reaction conditions in an extrusion reactor, a heatedmelt-blend reactor, a Banbury mill or other high-viscosity-materialblenders or mixers, for example, an extruder. (Where an extruder isreferred to in this disclosure, it should be understood that this isexemplary of the broader class of blenders or mixers which may be usedfor melt-blending according to the present invention.)

[0260] To carry out the melt reaction, it is desirable to establishsuitable extruder operating conditions for generating grafted polymericproduct having an effective percentage of or most or all of the monomergrafted on the polymer. The monomer should be grafted directly onto thepolyolefin, rather than forming dimeric, oligomeric, or homopolymericgraft moieties or, forming independent homopolymers.

[0261] One may generate graft copolymer exhibiting the desired qualitiesand performance characteristics by selecting, based on the teachings ofthe present specification, appropriate reactant feed rates as well asappropriate extruder operating conditions. These conditions include,among others, the proportions of the graftable monomer to the polyolefinand of the initiator to polymer or, alternatively, of the initiator tomonomer as well as the design of the extruder and its operatingconditions. The latter include, but are not limited to, the screw designand its size, barrel diameter and length, die configuration and opencross-section, barrel temperature, die temperature, screw speed,pre-extrusion and post-extrusion conditions, the reactant feed systems,the polymer feed hopper and the reactant addition ports.

[0262] With respect to the reactants, the contemplated minimum molarproportions are generally the same as that previously stated in thediscussion of the solvent based reaction. As outlined for the solventbased reaction, the reactants may be fed to the extruder, alternatively,as a mixture of components or separately, as individual components. Inthe preferred embodiment, the reactants, for example monomer andinitiator, are fed separately. It is also preferred to feed the polymeras the first reactant.

[0263] The reactants are fed to a suitable polyolefin extruder or othermelt-blend reactor. The operating conditions for the extruder and thedesign of the extruder, in terms of screw design and size, barreldiameter and length, die configuration and open cross-section, barreltemperature, die temperature, screw speed, pre-extrusion andpostextrusion conditions, the reactant feed systems, the polymer feedhopper and reactant addition ports, may be selected using routine skillin the extrusion field, to yield product with the desired qualities andperformance characteristics. During operation, the extruder can bemaintained under essentially aerobic conditions, or may be purged orblanketed with an inerting material, for example, nitrogen, carbondioxide, or argon, in order to create anaerobic operating conditions.

[0264] To carry out the melt reaction, the polyolefin feed must bebrought to its melt condition. Heating of the polymer may be achieved,among others, by using an external heat source preceding the extruder,by heating the extruder, alternatively, by means of the frictionresulting from mastication and flow of the polyolefin composition in theextruder, or by any combination of these expedients. The other reactantscan be heated to the desired reaction temperature either before or whilethey are fed to the extruder or while in the extruder. Since thetemperature of the polyolefin will, in part, determine the temperatureof the other reactants, the polyolefin may be brought to near thedesired reaction temperature, the temperature chosen so that essentiallyall of the initiator is consumed during the time allotted for thereaction.

[0265] The graftable monomer is metered into the extruder at a constantrate throughout the reaction through one or several discrete monomerfeed ports. The monomer may be fed either with or after the polyolefin,that is, either into the same extruder zone, or the addition of themonomer may be somewhat delayed, by being introduced downstream from thepolymer, or into a zone separated from the polymer feed hopper by anappropriate seal. The rate of addition of the graftable monomer or itsconcentration relative to polymer is adjusted to yield the desiredmonomer to polymer ratio in the final product.

[0266] While the monomer may be added neat, in a preferred embodiment,it is introduced “cut-back” with solvent in order to avoid localizedregions of elevated concentration. Representative solvents include baseoils conventionally used in lubricant compositions, as defined in thisspecification, mineral spirits, volatile solvents, polar solvents andother solvents known to those skilled in the art. The concentration ofmonomer relative to solvent ranges from about 1 wt % to about 100 wt %.The cut-back solvent can be used in essentially the same proportions,with respect to the amount of monomer, as noted for the solventreaction.

[0267] Similarly, the initiator may be metered into the extruder at aconstant rate throughout the reaction through one or several discreteinitiator feed ports. The initiator may be fed either before, with, orafter the monomer, that is, either into the same extruder zone or into azone separated from the monomer feed by an appropriate seal. The rate ofaddition of the initiator, or its concentration relative to monomer, isadjusted to yield the desired monomer to polymer ratio in the finalproduct while maintaining satisfactory physical and performanceproperties. While the monomer may be added neat, in a preferredembodiment, it is introduced “cut-back” with solvent in order to avoidlocalized regions of elevated concentration.

[0268] In some embodiments, the initiator may be added in a fashion sothat there is a large excess of both the graftable monomer and thepolyolefin present during essentially the entire reaction. In otherembodiments, the initiator may be added along with the graftablemonomer, either at the same rate or a somewhat faster or slower rate, sothere is an excess of polyolefin to unreacted initiator, so the amountof unreacted graftable monomer is comparable to the amount of unreactedinitiator.

[0269] In one embodiment, the initiator is added through a feed portdownstream from that through which the graftable monomer has been added.In another embodiment, the initiator may be added along with thegraftable monomer, either at the same rate (measured as a percentage ofthe rate of addition of the polyolefin) or at a somewhat faster orslower rate. Once operational equilibrium for the extruder has beenestablished, the ratios of monomer to polyolefin and of initiator tomonomer remain essentially fixed and the reactant flow rates remainessentially constant during its operation. Oftentimes, flow rates arechosen so that the concentration of graftable monomer is greater than orcomparable to the concentration of unreacted initiator.

[0270] The extruder generally operates continuously during which timethe ingredients (reactants) are added at a uniform rate. At times it isdesirable to introduce the reactants sequentially along the extruderbarrel. Such delays in the introduction of reactants can be generated byaligning the reactant feed ports sequentially along the extruder barrelor, alternatively, by introducing “seal” elements into the design of theextruder which serve to physically segment the extruder into distinctzones along the barrel. The reactants may, then, be fed, via thereactant feed ports, into these zones.

[0271] In alternate embodiments of this invention, as explained above,the monomer and initiator can be introduced together at the appropriaterelative concentration. By carefully selecting the operating conditions,in terms of residence times, extruder zone temperatures, screw speed,reactant feed rates, etc., the extruder process may be customized forvarious polymers cited herein, any of the graftable monomers coveredherein, the initiators cited herein, and, if required, inhibitors, or,alternatively, to yield product having specific monomer to polymerratios or other specifically desired properties.

[0272] In a preferred embodiment of the melt reaction process, thegrafted polyolefin product will be cut-back with solvent in order tofacilitate handling of the graft polymer and lubricant blending usingthe graft product.

[0273] III. Composition and Materials for Preparation of Lubricating OilCompositions

[0274] A. Composition of Lubricating Oil Compositions

[0275] The lubricating oil compositions of the present inventionpreferably comprise the following ingredients in the stated proportions:

[0276] A. from about 70% to about 99% by weight, alternatively fromabout 80% to about 99% by weight, alternatively from about 88% to about99% by weight, of one or more base oils (including base oil carried overfrom the making of the grafted polyolefin);

[0277] B. from about 0.05% solids to about 10% solids by weight,alternatively from about 0.05% solids to about 5% solids by weight,alternatively from about 0.15% solids to about 2% solids by weight,alternatively from about 0.15% solids to about 1.5% solids by weight,alternatively from 0.25% solids to about 1.5% solids by weight,alternatively from 0.4% solids by weight to 1.5% solids by weight,alternatively 0.5% solids by weight to 1.5% solids by weight, of one ormore of the grafted polyolefins made according to this specification(i.e., not including base oil carried over from the making of thegrafted polyolefin);

[0278] C. from about 0.0% solids to 2.0% solids by weight, alternativelyfrom about 0.0% solids to about 1.0% solids by weight, alternativelyfrom about 0.05% solids to about 0.7% solids by weight, alternativelyfrom about 0.1% solids to about 0.7% solids by weight, of one or morepolyolefins other than the grafted polyolefins according to the presentinvention;

[0279] D. from 0.0% to about 15% by weight, alternatively from about0.5% to about 10% by weight, alternatively from about 0.5% to about 6%by weight, or alternatively from about 0.7% to about 6%, of one or moredispersants which are not grafted polyolefins according to the presentinvention;

[0280] E. from about 0.3% to 6% by weight, alternatively from about 0.3%to 4% by weight, alternatively from about 0.5% to about 3% by weight,alternatively from about 0.5 to about 2% by weight, of one or moredetergents;

[0281] F. from about 0.01% to 3% by weight, alternatively from about0.04% to about 2.5% by weight, alternatively from about 0.06% to about2% by weight, of one or more anti-wear agents;

[0282] G. from about 0.01% to 5% by weight, alternatively from about0.01% to 2% by weight, alternatively from about 0.05% to about 1.5% byweight, alternatively from about 0.1% to about 1% by weight, of one ormore anti-oxidants; and

[0283] H. from about 0.0% to 4% by weight, alternatively from about 0.0%to 3% by weight, alternatively from about 0.005% to about 2% by weight,alternatively from about 0.005% to about 1.5% by weight, of minoringredients such as, but not limited to, friction modifiers, pour pointdepressants, and anti-foam agents.

[0284] The percentages of D through H may be calculated based on theform in which they are commercially available. The function andproperties of each ingredient identified above and several examples ofingredients are summarized in the following sections of thisspecification.

[0285] B. Base Oils

[0286] Any of the petroleum or synthetic base oils previously identifiedas process solvents for the graftable polyolefins of the presentinvention can be used as the base oil. Indeed, any conventionallubricating oil, or combinations thereof, may also be used.

[0287] C. Composition of Grafted Polyolefins

[0288] The grafted polyolefins according to the present inventioncontain:

[0289] at least about 1 mole,

[0290] alternatively at least about 2 moles,

[0291] alternatively at least about 3 moles,

[0292] alternatively at least about 4 moles,

[0293] alternatively at least about 5 moles,

[0294] alternatively at least about 6 moles,

[0295] alternatively at least about 7 moles,

[0296] alternatively at least about 8 moles,

[0297] alternatively at least about 9 moles,

[0298] alternatively at least about 10 moles,

[0299] alternatively at least about 11 moles,

[0300] alternatively at least about 12 moles,

[0301] alternatively at least about 13 moles,

[0302] alternatively at least about 14 moles,

[0303] alternatively at least about 15 moles,

[0304] alternatively at least about 16 moles,

[0305] alternatively at least about 17 moles,

[0306] alternatively at least about 18 moles,

[0307] alternatively at least about 19 moles,

[0308] alternatively at least about 20 moles,

[0309] alternatively at least about 22 moles,

[0310] alternatively at least about 24 moles,

[0311] alternatively at least about 26 moles,

[0312] alternatively at least about 28 moles,

[0313] alternatively at least about 30 moles,

[0314] alternatively at least about 32 moles,

[0315] alternatively at least about 34 moles,

[0316] alternatively at least about 36 moles,

[0317] alternatively at least about 38 moles,

[0318] alternatively at least about 40 moles,

[0319] alternatively at least about 50 moles,

[0320] alternatively at least about 60 moles,

[0321] alternatively at least about 70 moles,

[0322] alternatively at least about 80 moles,

[0323] alternatively at least about 90 moles,

[0324] alternatively at least about 100 moles,

[0325] alternatively at least about 120 moles

[0326] of grafted monomer per mole of the original polyolefin, and

[0327] at least about 0.2% by weight,

[0328] alternatively at least about 0.3% by weight,

[0329] alternatively at least about 0.4% by weight,

[0330] alternatively at least about 0.5% by weight,

[0331] alternatively at least about 0.6% by weight,

[0332] alternatively at least about 0.7% by weight,

[0333] alternatively at least about 0.8% by weight,

[0334] alternatively at least about 0.9% by weight,

[0335] alternatively at least about 1.0% by weight,

[0336] alternatively at least about 1.1% by weight,

[0337] alternatively at least about 1.2% by weight,

[0338] alternatively at least about 1.3% by weight,

[0339] alternatively at least about 1.4% by weight,

[0340] alternatively at least about 1.5% by weight,

[0341] alternatively at least about 1.6% by weight,

[0342] alternatively at least about 1.7% by weight,

[0343] alternatively at least about 1.8% by weight,

[0344] alternatively at least about 1.9% by weight,

[0345] alternatively at least about 2.0% by weight,

[0346] alternatively at least about 3.0% by weight,

[0347] alternatively at least about 4.0% by weight,

[0348] alternatively at least about 5.0% by weight,

[0349] alternatively at least about 6.0% by weight,

[0350] alternatively at least about 7.0% by weight,

[0351] alternatively at least about 8.0% by weight,

[0352] alternatively at least about 9.0% by weight,

[0353] alternatively at least about 10% by weight,

[0354] alternatively at least about 12% by weight,

[0355] alternatively at least about 20% by weight,

[0356] of grafted moieties per unit weight of the grafted polyolefin(generally calculated by assuming a 200 dalton molecular weight for themonomer and a 100,000 dalton molecular weight for the polymer).

[0357] The molecular weight of the grafted polyolefin will usually becomparable to that of the ungrafted polyolefin from which it is made.

[0358] The grafted polyolefins can be used in place of part or all ofthe viscosity index improving polyolefins conventionally used in suchformulations. They can also be used in place of part or all of thedispersants conventionally used in such formulations, as they help keepin suspension the impurities which develop in lubricating oils duringuse.

[0359] The use of the present grafted dispersant polyolefins has manysignificant formulation advantages. The low-temperature viscosityincrease normally caused by the presence of conventional dispersants maybe largely eliminated. This allows higher-viscosity and, thus, lessvolatile base oils to be used. As a result, reduced volatility engineoil formulations, such as 5W-20, 5W-30 and 10W-30, may be formulated.Another advantage of the present invention is that lubricantcompositions that use the grafted polyolefin, in general, are much lessexpensive than lubricant compositions that use conventional dispersants.This means that the formulations of the present invention are moreeconomical than previous lubricant formulations which use less-graftedpolyolefins and more of the conventional dispersants.

[0360] Moreover, an improvement in wear is achieved when the presentinvention is used and the amount of the conventional dispersant isreduced. Dispersants, it is believed, both interact with the anti-wearagents and compete with them for sites on the parts being lubricated,thus reducing their effectiveness. The inventors theorize that thisinteraction reduces the efficacy of the anti-wear agents. See ExxonChemical Patents, Inc. v. Lubrizol Corporation, 64 F.3d 1553 (Fed. Cir.1995). That opinion is incorporated here by reference.

[0361] Grafted polyolefins disclosed in prior art can be used incombination with the grafted polyolefins disclosed in the presentinvention. Previously known grafted polyolefins, some of which also maydisplace part of other dispersing agents, include those disclosed inU.S. Pat. No. 4,092,255, column 1, lines 47-53: grafted polyolefinsresulting from the grafting of acrylonitrile or aminoalkyl methacrylateson amorphous polyolefins of ethylene and propylene, or also polyolefinsobtained by radical polymerization of acrylates or alkyl methacrylateswith vinyllactams such as N-vinylpyrrolidinone or aminoalkylmethacrylates.

[0362] Other grafted polyolefins useful herein include those disclosedin U.S. Pat. No. 4,092,255 from column 2, line 1, to column 5, line 12,which is hereby incorporated herein by reference. The constituents ofthose grafted polyolefins (polyolefins, initiators, and graftablemonomers) can also be used to prepare the grafted polyolefins accordingto the present invention.

[0363] D. Non-Grafted Polyolefins

[0364] The conventional viscosity index improving polyolefins can beused in the formulations according to the present invention. These areconventionally long-chain polyolefins. Several examples of polyolefinscontemplated for use herein include those suggested by U.S. Pat. No.4,092,255, column 1, lines 29-32: polyisobutenes, polymethacrylates,polyalkylstyrenes, partially hydrogenated copolymers of butadiene andstyrene, amorphous polyolefins of ethylene and propylene,ethylene-propylene diene polymers, polyisoprene, and styrene-isoprene.

[0365] E. Other Dispersants

[0366] Other dispersants (i.e. dispersants which are not the graftcopolymers described previously) also help suspend insoluble engine oiloxidation products, thus preventing sludge flocculation andprecipitation or deposition of particulates on metal parts. Suitabledispersants include high molecular weight alkyl succinimides and thereaction products of oil-soluble polyisobutylene succinic anhydride withethylene amines such as tetraethylene pentamine and borated saltsthereof.

[0367] Such conventional dispersants are also contemplated for useherein, although frequently they can be used at reduced concentrationswhen the grafted polyolefins according to the present invention areused. Several examples of dispersants include those listed in U.S. Pat.No. 4,092,255, column 1, lines 38-41: succinimides or succinic esters,alkylated with a polyolefin of isobutene or propylene, on the carbon inthe alpha position of the succinimide carbonyl. These additives areuseful for maintaining the cleanliness of an engine or other machinery.

[0368] F. Detergents

[0369] Detergents to maintain engine cleanliness can be used in thepresent lubricating oil compositions. These materials include the metalsalts of sulfonic acids, alkyl phenols, sulfurized alkyl phenols, alkylsalicylates, naphthenates, and other soluble mono- and dicarboxylicacids. Basic (vis, overbased) metal salts, such as basic alkaline earthmetal sulfonates (especially calcium and magnesium salts) are frequentlyused as detergents. Such detergents are particularly useful for keepingthe insoluble particulate materials in an engine or other machinery insuspension. Other examples of detergents contemplated for use hereininclude those recited in U.S. Pat. No. 4,092,255, column 1, lines 35-36:sulfonates, phenates, or organic phosphates of polyvalent metals.

[0370] G. Anti-Wear Agents

[0371] Anti-wear agents, as their name implies, reduce wear of metalparts. Zinc dialkyldithiophosphates and zinc diaryldithiophosphates andorgano molybdenum compounds such as molybdenum dialkyldithiocarbamatesare representative of conventional anti-wear agents.

[0372] H. Anti-Oxidants

[0373] Oxidation inhibitors, or anti-oxidants, reduce the tendency oflubricating oils to deteriorate in service. This deterioration can beevidenced by increased oil viscosity and by the products of oxidationsuch as sludge and vamish-like deposits on the metal surfaces. Suchoxidation inhibitors include alkaline earth metal salts ofalkylphenolthioesters having preferably C₅ to C₁₂ alkyl side chains,e.g., calcium nonylphenol sulfide, dioctylphenylamine,phenyl-alpha-naphthylamine, phosphosulfurized or sulfurizedhydrocarbons, and organo molybdenum compounds such as molybdenumdialkyldithiocarbamates.

[0374] I. Pour Point Depressants

[0375] Pour point depressants, otherwise known as lube oil flowimprovers, lower the temperature at which the fluid will flow or can bepoured. Such additives are well known. Typical of those additives whichoptimize the low temperature fluidity of a lubricant areC₈-C₁₈-dialkylfumarate vinyl acetate copolymers, and polymethacrylates.

[0376] J. Minor Ingredients

[0377] Many minor ingredients which do not prevent the use of thepresent compositions as lubricating oils are contemplated herein. Anon-exhaustive list of other such additives includes rust inhibitors, aswell as extreme pressure additives, friction modifiers, antifoamadditives, and dyes.

[0378] IV. Test Methods

[0379] A. % Nitrogen

[0380] This test is used to determine the concentrations of nitrogen onthe polyolefin and on the process fluid (assuming the reaction iscarried out in a process solvent). The results of this test are used todetermine the degree of grafting.

[0381] In order to accurately determine the amount of nitrogen graftedonto each of the two components during the grafting reaction, eachcomponent in the reaction mixture first must be isolated and thenindividually analyzed using the ANTEK Elemental Analyzer. This isaccomplished as follows.

[0382] Prior to analysis, the reaction mixture is separated into itsindividual components. Sufficient reaction mixture to contain between0.1 and 0.15 grams of the grafted polyolefin is placed in a suitableglass vial. Sufficient heptane is added to give a resulting solutioncontaining approximately 2% polyolefin solids.

[0383] The grafted polyolefin is then precipitated from this solution byslowly adding the solution to a beaker containing an excess of acetone.The precipitate is collected and rinsed several times with acetone. Theprecipitate is then placed on a watch glass and dried at 60° C. in anoven for about 18 hours. The process fluid (or solvent) used during thegrafting process is prepared for analysis by separating the acetone andheptane from the “acetone-heptane” contaminated process fluid.

[0384] The two samples, the extracted polyolefin and the process fluid,are then analyzed separately on the ANTEK Elemental Analyzer (Model 9000VSN Solid Auto Sampler). The total sample response is recorded and theintegrated area is determined using ANTEK V366 Software. The instrumentresponse is then calibrated with a suitable standard such as Erucimide(4.148% Nitrogen CAS # 112-84-5). The Calibration data are then utilizedto convert the integrated sample area into percentages of nitrogen.

[0385] The percentage of nitrogen on the polyolefin (corrected for anyresidual process fluid in the dried polymer) and on the solvent can beeasily converted to the percentage of grafted nitrogenous monomer on thepolyolefin by dividing by the percent by weight of nitrogen in themonomer. For example, when the monomer is the reaction product of maleicanhydride and 4-aminodiphenylamine, the percentage of nitrogen on thepolyolefin can be converted to the percentage of grafted monomer on thepolyolefin by dividing by 0.106 (since the monomer contains about 10.6%nitrogen by weight).

[0386] B. Determination of Aromatic Content of Solvent

[0387] The aromatic content of the solvent or process fluid used in thegrafting reactions is determined by measuring its absorbance overwavelengths ranging from 190 nm to 360 nm in a solution of knownconcentration. A small amount of the test sample is dissolved incyclohexane (spectroscopic grade) and the spectrum of the test solutionis scanned over the above wavelength range. Measurements are carried outat the peak maxima over the ranges of 190-210 nm, 220-240 nm, and260-280 nm. These positions correspond to the strongest absorption ofmono-, di-, and polycyclic aromatics. Usually the maxima are located at203 nm, 226 nm, and 270 nm.

[0388] The absorbances at these positions, corrected for the baselinecell absorbance, are used to calculate the concentrations of mono-, di-,and polycyclic aromatics. The aromatics total is the sum of theconcentrations of these three aromatic species. In carrying out thesecalculations, the molar absorptivities of the sample, determined at thethree specified wavelength ranges, are utilized.

[0389] C. Infrared Spectroscopy

[0390] Infrared spectroscopy was employed to assess qualitatively thechemical composition of certain grafted products and also to assay thedegree of grafting of monomer onto the polymer backbone. The instrumentused to collect the data is the Perkin-Elmer Model C 1720 InfraredFourier Transform Spectrometer. Data was gathered using 4 cm⁻¹resolution.

[0391] As previously described in connection with % Nitrogen analysis,prior to analysis, the reaction mixture is separated into its individualcomponents—the grafted polyolefin and process fluid. The procedure to befollowed was described previously with respect to the Nitrogen analysis.In contrast with the nitrogen analysis, for this analysis, the liquidphase containing the process fluid need not be retained for purposes ofthe Infrared analysis.

[0392] The extracted polymer is converted into a thin film using aCarver Model C Laboratory Press operated at 8,000 to 10,000 pounds at atemperature of 150 ° C. The thin film is then aligned in the samplecompartment of the spectrometer and a spectrum is collected using 4wavenumber resolution.

WORKING EXAMPLES Example 1 Laboratory Preparation of Reaction Productfor Grafting

[0393] In this example an ethylenically-unsaturated reaction productcontaining both nitrogen and oxygen was prepared. A 500 ml reactorequipped with an electric heating mantle, stirrer, thermometer andwater-cooled reflux condenser was charged with 70 ml of acetone and 5.28g of maleic anhydride. The maleic anhydride was allowed to dissolve inthe acetone. A second solution was prepared containing 9.93 g of4-aminodiphenylamine dissolved in 50 ml of acetone. The temperature ofthe maleic anhydride solution was raised to 60° C. While the maleicanhydride-acetone solution was kept at temperature and refluxing, fiveequal aliquots of the 4-aminodiphenylamine solution were introduced over140 minutes (35 minutes intervals between aliquot additions). Thereaction proceeded for an additional 90 minutes until the reaction wasconsidered complete based upon TLC spotting. The TLC experiments werecarried out using 5 cm×20 cm silica gel 60 F₂₅₄ coated plates marketedby EM Science. The solvent was a mixture of 5.6% by volume ethylalcohol, 33.3% by volume ethyl acetate and 61.1% by volume heptane.After the reaction was complete, the solution was allowed to cool toroom temperature. Upon cooling, the reaction product precipitated fromsolution. The precipitate was filtered, partially purified and dried.NMR analysis indicated that the reaction product compriseddiphenylaminomaleimide and the corresponding amic acid which is believedto be mono-diphenylaminoamide of maleic acid. This reaction product issuitable for grafting onto a polyolefin according to the methodsdescribed herein, to provide a dispersent viscosity index improver.

Example 2 Laboratory Preparation of Monomer for Grafting

[0394] In this example an ethylenically-unsaturated monomer containingboth nitrogen and oxygen was prepared. A 500 ml reactor equipped with anelectric heating mantle, stirrer, thermometer and water-cooled refluxcondenser was charged with 150 ml of N,N-dimethyl formamide and 20.1 gof maleic anhydride. The reactor temperature was raised to 150° C. andthe solution was allowed to reflux at this temperature. While at thistemperature, 37.9 g of 4-aminodiphenylamine were quickly introduced intothe solution. The reaction proceeded for 120 minutes until the reactionwas considered complete based upon TLC spotting as described inExample 1. The N,N-dimethyl formamide was then vacuum stripped and thereaction product was filtered and dried. This reaction product issuitable for grafting onto a polyolefin to provide a dispersantviscosity index improver.

Example 3 Laboratory Preparation of Monomer for Grafting

[0395] In this example an ethylenically-unsaturated monomer containingboth nitrogen and oxygen was prepared. A 500 ml reactor equipped with anelectric heating mantle, stirrer, thermometer and water-cooled refluxcondenser was charged with 14.3 ml of N,N-dimethyl formamide and 7.0 gof maleic anhydride. The reactor temperature was raised to 150° C. andthe solution was allowed to reflux at this temperature. While at thistemperature, 13.2 g of 4-aminodiphenylamine were quickly introduced intothe solution. The reaction proceeded for 180 minutes until the reactionwas considered complete based upon TLC spotting as described inExample 1. The reaction product, without subsequent purification orseparation of components, is suitable for the grafting reaction with apolyolefin to provide a dispersant viscosity index improver.

Example 4 Laboratory Preparation of Graft Polymer

[0396] A resin kettle equipped with an electric heating mantle, stirrer,thermometer and gas inlet was charged with 500 g of a polymer solution.The gas inlet permits the gas to be fed either below or above thesurface of the solution. The polymer solution was prepared by dissolving12.5 weight percent polyolefin in a commercially available hydrorefinedbase stock. The solution was heated to 170° C. During heating thesolution was purged with an inerting gas (CO₂) fed below the surface ofthe solution. When the solution reached the temperature of 170° C., thepurge gas was redirected to flow over the surface of the polymersolution. With the polymer solution at this temperature, two solutions,one containing monomer from Example 1 and the other containingdi-t-butyl peroxide initiator were introduced. The monomer solution wasprepared by dissolving 11.6 g of the monomer from Example I in 25 ml ofTHF. The initiator solution was prepared by dissolving 2.4 g ofdi-t-butyl peroxide in 60 ml of heptane. The monomer solution wasmetered into the resin kettle over a sixty minutes period. 30 ml of theinitiator solution were metered into the resin kettle over the samesixty minutes period. The remaining 30 ml of initiator solution were fedto the reactor over the following sixty minutes period. After all of thereactants were added, the mixture was allowed to react for an additionalsixty minutes for a total elapsed reaction time of three hours. Aftercompletion of the reaction, the polymer was precipitated using acetone,and then dried, as described above in the section entitled “TestMethods”, and then analyzed for percent nitrogen using the ANTEKElemental Analyzer. An Infrared spectrum of the precipitated polymerexhibited absorbances at 3364 cm⁻¹, 1774 cm⁻¹, 1708 cm⁻¹, 1597 cm⁻¹,1515 cm⁻¹ and 748 cm⁻¹. The grafted polymer contained 0.53 percentnitrogen using the Antek Elemental Analyzer and had a calculated monomerto polymer mole ratio of about 18.9:1.

Example 5 Laboratory Preparation of Graft Copolymer

[0397] A resin kettle was equipped with an electric heating mantle,stirrer, thermometer and gas inlet. The gas inlet permits the gas to befed either below or above the surface of the solution. The resin kettlewas charged with 5 g of an ethylene-propylene copolymer and 95 g of1,2,4-trichlorobenzene. The reactor was then heated to 170° C. withvigorous stirring for 6 hours until the polymer was fully dissolved.During heating, the solution was purged with an inerting gas fed belowthe surface of the solution. After dissolution, the polymer solution wasallowed to cool to room temperature.

[0398] After the polymer solution cooled to room temperature, 0.92 g ofmonomer from Example 1 was added. The solution was reheated to 170° C.During heating, the solution was purged with an inerting gas fed belowthe surface of the solution. When the solution reached the reactiontemperature of 170° C., the purge was redirected to flow over thesurface of the polymer solution. A solution containing 0.12 g ofdi-t-butyl peroxide in 5 ml of 1,2,4-trichlorobenzene was prepared. Thiswas fed slowly, over a 60 minutes period, into the mixture of polymerand monomer. The reaction mixture was then allowed to react for anadditional sixty minutes for a total elapsed reaction time of 120minutes. After completion of the reaction, a small sample (<5 ml) ofpolymer solution was collected and the polymer precipitated usingacetone and then dried as previously described. An Infrared spectrum ofthe precipitated polymer exhibited absorbances at 3364 cm⁻¹, 1774 cm⁻¹,1708 cm⁻¹, 1597 cm⁻¹, 1515 cm⁻¹ and 748 cm⁻¹. The grafted polymercontained 0.44 percent nitrogen and had a calculated monomer to polymermole ratio of about 15.7:1.

Example 6 Laboratory Preparation of Graft Copolymer

[0399] The reaction mixture from Example 5 was heated to 170° C. whilepurging the solution with an inerting gas fed below the surface of thesolution. When the solution reached the reaction temperature of 170° C.,the purge was redirected to flow over the surface of the reactionmixture and a second charge of initiator was fed into the reactionmixture. Again, the initiator was fed as a solution containing 0.12 g ofdi-t-butyl peroxide (initiator) in 5 ml of 1,2,4-trichlorobenzene. Aspreviously, the 5 ml were fed slowly into the reaction mixture over a 60minute period. The reaction mixture was, again, allowed to react for anadditional 60 minutes. The total elapsed reaction time for Examples 5and 6 was four hours. After completion of the reaction, the polymer wasprecipitated using acetone and then dried. An Infrared spectrum of theprecipitated polymer exhibited absorbances at 3364 cm⁻¹, 1774 cm⁻¹, 1708cm⁻¹, 1597 cm⁻¹, 1515 cm⁻¹ and 748 cm⁻¹. The grafted polymer contained1.09 percent nitrogen and had a calculated monomer to polymer mole ratioof about 39:1.

Example 7 Laboratory Preparation of Graft Copolymer

[0400] A resin kettle equipped with an electric heating mantle, stirrer,thermometer and gas inlet was charged with 500 g of a polymer solution.The gas inlet permits the gas to be fed either below or above thesurface of the solution. The polymer solution was prepared by dissolving12.5 weight percent polyolefin in a commercially available hydrorefinedbase stock. The solution was heated to 170° C. During heating thesolution was purged with an inerting gas (CO₂) fed below the surface ofthe solution. When the solution reached the temperature of 170° C., thepurge gas was redirected to flow over the surface of the polymersolution. With the polymer solution at temperature, two solutions, onecontaining monomer from Example 3 and the other containing di-t-butylperoxide, were introduced. The monomer solution was prepared by bringingthe volume of monomer from Example 3 up to 50 ml by diluting with THF(Tetrahydrofuran). The initiator solution was prepared by dissolving 3.0g of di-t-butyl peroxide in 60 ml of heptane. The monomer solution wasmetered into the resin kettle over a sixty minutes period. 30 ml of theinitiator solution were metered into the resin kettle over the same 60minute period. The mixture was allowed, then, to react for an additional30 minutes for a total elapsed reaction time of 150 minutes. Aftercompletion of the reaction, the polymer was precipitated with acetone,dried as previously described, and then analyzed for percent nitrogenusing the ANTEK Elemental Analyzer. An Infrared spectrum of theprecipitated polymer exhibited absorbances at 3364 cm⁻¹, 1774 cm⁻¹, 1708cm⁻¹, 1597 cm⁻¹, 1515 cm⁻¹ and 748 cm⁻¹. The grafted polymer contained0.22 percent nitrogen using the ANTEK Elemental Analyzer and had acalculated monomer to polymer mole ratio of about 7.9:1.

Example 8 Laboratory Preparation of Graft Copolymer

[0401] The reaction mixture from Example 7 is heated to 170° C. whilepurging the solution with an inerting gas fed below the surface of thesolution. When the solution reaches the reaction temperature of 170° C.,the purge is redirected to flow over the surface of the reaction mixtureand a second charge of initiator is fed into the reaction mixture tocontinue the reaction. The initiator, for example, is fed as a solutioncontaining about 1.5 g of di-t-butyl peroxide in 30 ml of heptane. The30 ml is fed slowly into the reaction mixture over a 60 minute period.The reaction mixture is allowed to react for an additional 60 minutes.The total elapsed reaction time for Examples 7 and 8 is 120 minutes.After completion of the reaction, the polymer is precipitated usingacetone and then dried. An Infrared spectrum of the precipitated polymerexhibits absorbances at 3364 cm⁻¹, 1774 cm⁻¹, 1708 cm⁻¹, 1597 cm⁻¹, 1515cm⁻¹ and 748 cm⁻¹ and exhibits a monomer to polymer mole ratio of about12:1.

Example 9 Laboratory Preparation of Monomer for Grafting

[0402] In this example an ethylenically-unsaturated monomer containingboth nitrogen and oxygen is prepared. A 500 ml reactor equipped with anelectric heating mantle, stirrer, thermometer and water-cooled refluxcondenser is charged with 70 ml of acetone and 5.28 g of maleicanhydride. The maleic anhydride is allowed to dissolve in the acetone. Asecond solution is prepared containing 9.93 g of 4-aminodiphenylaminedissolved in 50 ml of acetone. The temperature of the maleic anhydridesolution is raised to 60° C. While refluxing the maleic anhydridesolution, the 4-aminodiphenylamine solution is introduced, eitherslowly, over time, or rapidly into the maleic anhydride solution. Thereaction proceeds for an additional 90 minutes until the reaction isconsidered complete based upon TLC spotting. This reaction product issuitable for grafting onto a polyolefin according to the methods herein,to provide a dispersant viscosity index improver.

Example 10 Melt Reaction Preparation of Graft Copolymer

[0403] The extruder used is an oil heated twin screw counter rotatingunit having multiple reactant injection ports. It is hot oil heated.

[0404] Attentive control of reactant feed rates is highly advisable whencarrying out melt or extruder reactions. The feed system for polymerbales includes a bale cutter to cut the bales, a grinder to granulatethe polymer, and a conveyor and weigh-belt to feed the ground polymer tothe extruder hopper. This system is designed to deliver the polyolefin,at a continuous and uniform rate in order to meet the targeted polymerfeed rate. The ground polymer is conveyed along the extruder and meltedwithin the inlet zone of the extruder.

[0405] The feed systems for the other reactants are also capable ofdelivering the reactants under controlled conditions. The monomerreaction mixture, prepared in accordance with the procedure as outlinedin Example 3, is metered into the extruder using a Variable SpeedMetering Pump capable of delivering fluids at discharge pressures of upto 1500 psig. This system is capable of-delivering the monomer at acontinuous and uniform rate in order to meet the targeted monomer feedrate, which is desirable for a melt reaction.

[0406] The peroxide initiator solution is also metered with a variablespeed metering pump capable of delivering fluids at discharge pressuresof up to 1500 psig. This system is, as noted, is capable of deliveringthe peroxide at a continuous and uniform rate in order to meet thetargeted peroxide feed rate.

[0407] By setting appropriate conditions of temperature and reactantfeed rates, the monomer is grafted onto the melt polymer forming a graftpolyolefin exhibiting absorbances at 3364 cm⁻¹, 1774 cm⁻¹, 1708 cm⁻¹,1597 cm⁻¹, 1515⁻¹ cm and 748 cm⁻¹. If desired, multiple monomer andinitiator feed ports may be used.

[0408] The graft polymer is either formed into pellets or is dissolvedin an appropriate solvent thereby forming a dispersant viscosity indeximprover in convenient form for transport and use to prepare lubricatingoil compositions .

Example 11 Alternate Reaction Components

[0409] The experiments of Examples 1 -10 are repeated, using conditionssimilar to those of the previous Examples, with each possiblecombination of the acylating agents, amines, solvents, polyolefins,graftable monomers, and initiators identified earlier in thisapplication. Grafted polyolefins are formed which have utility forincreasing the viscosity index of a lubricating oil.

What is claimed is:
 1. A reaction product of (a) an amine selected fromthe group consisting of primary amines and secondary amines and (b) anacylating agent having at least one point of ethylenic unsaturation;wherein the reaction product comprises a nitrogen-and oxygen-containingcompound having at least one point of ethylenic unsaturation.
 2. Thereaction product of claim 1, wherein the acylating agent is selectedfrom the group consisting of monounsaturated C₄ to C₅₀ dicarboxylicacids; monounsaturated C₃ to C₅₀ monocarboxylic acids; anhydridesthereof; and combinations of any of the foregoing.
 3. The reactionproduct of claim 1, wherein the acylating agent is selected from thegroup consisting of acrylic acid, crotonic acid, methacrylic acid,maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconicanhydride, citraconic acid, citraconic anhydride, mesaconic acid,glutaconic acid, chloromaleic acid, aconitic acid, methylcrotonic acid,sorbic acid, 3-hexenoic acid, 10-decenoic acid,2-pentene-1,3,5-tricarboxylic acid, cinnamic acid, and C₁ to C₄ alkylacid esters of the foregoing, and combinations of any of the foregoing.4. The reaction product of claim 1, wherein the acylating agent ismaleic acid.
 5. The reaction product of claim 1, wherein the acylatingagent is maleic anhydride.
 6. The reaction product of claim 1, whereinthe reaction product is formed by contacting the amine and the acylatingagent at a weight ratio in the range of from about 0.3:1 to about 3:1.7. The reaction product of claim 6, wherein the acylating agent ismaleic acid; and wherein said weight ratio is about 0.6:1 to about 2:1.8. The reaction product of claim 6, wherein the acylating agent ismaleic anhydride; and wherein said weight ratio is about 0.3:1 to about2:1.
 9. The reaction product of claim 7, wherein the amino-aromaticcompound is 4-aminodiphenylamine.
 10. The reaction product of claim 9,wherein the amino-aromatic compound is 4-aminodiphenylamine.
 11. Thereaction product of claim 1, wherein the reaction product comprises amixture of graftable monomers.
 12. The reaction product of claim 1,wherein the reaction product comprises a mixture of an imide and acorresponding amic acid of the imide.
 13. The reaction product of claim1, wherein the reaction product has at least two points of ethylenicunsaturation.
 14. The reaction product of claim 1, wherein the amine isselected from the group consisting of alkyl amines, alkyl polyamines,polyoxyalkylene polyamines and amino-aromatic compounds.
 15. Thereaction product of claim 1, wherein the amine comprises anamino-aromatic compound having the formula:

in which Ar is an aromatic ring, R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a branched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical is an alkyl, alkenyl,alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkyl radical, R₂ is—NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, —CH₂—(CH₂)_(n)—NH₂, or --aryl--NH₂, inwhich n and m each has a value from 1 to 10, and R₃ is hydrogen or analkyl, alkenyl, alkoxyl, aralkyl, or alkaryl radical having from 4 to 24carbon atoms.
 16. The reaction product of claim 1, wherein the aminecomprises an amino-aromatic compound having the formula:

in which R₄, R₅ and R₆ are hydrogen or a linear or branched hydrocarbonradical containing from 1 to 10 carbon atoms and the radical is analkyl, alkenyl, alkoxyl, alkyaryl, aryalkyl, hydroxyalkyl, or aminoalkylradical, and R₄, R₅ and R₆ are the same or different.
 17. The reactionproduct of claim 1, wherein the amine is an amino-aromatic compoundselected from the group consisting of aminocarbazoles, aminoindoles,amino-indazolinones, aminomercaptotriazole, and aminoperimidines.
 18. Amethod of making a nitrogen- and oxygen-containing monomer having atleast one point of ethylenic unsaturation, the method comprising thesteps of: A. providing an acylating agent having at least one point ofethylenic unsaturation; B. providing an amine selected from the groupconsisting of primary amines and secondary amines; C. contacting theacylating agent and the amine, optionally in the presence of a solvent;and D. heating the acylating agent and the amine to form a reactionproduct of the acylating agent and the amine.
 19. The method of claim18, wherein the acylating agent is selected from the group consisting ofmonounsaturated C₄ to C₅₀ dicarboxylic acids; monounsaturated C₃ to C₅₀monocarboxylic acids; anhydrides thereof; and combinations of any of theforegoing.
 20. The method of claim 18, wherein the acylating agent isselected from the group consisting of acrylic acid, crotonic acid,methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconicacid, itaconic anhydride, citraconic acid, citraconic anhydride,mesaconic acid, glutaconic acid, chloromaleic acid, aconitic acid,methylcrotonic acid, sorbic acid, 3-hexenoic acid, 10-decenoic acid,2-pentene-1,3,5-tricarboxylic acid, cinnamic acid, and C₁ to C₄ alkylacid esters of the foregoing, and combinations of the foregoing.
 21. Themethod of claim 18, wherein the acylating agent is maleic acid.
 22. Themethod of claim 18, wherein the acylating agent is maleic anhydride. 23.The method of claim 18, wherein the amine is selected from the groupconsisting of alkyl amines, alkyl polyamines, polyoxyalkylene polyaminesand amino-aromatic compounds.
 24. The method of claim 18, wherein theamine comprises an amino-aromatic compound having the formula:

in which Ar is an aromatic ring, R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a branched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical is an alkyl, alkenyl,alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkyl radical, R₂ is—NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, —CH₂—(CH₂)_(n)—NH₂, or --aryl--NH₂, inwhich n and m each has a value from 1 to 10, and R₃ is hydrogen or analkyl, alkenyl, alkoxyl, aralkyl, or alkaryl radical having from 4 to 24carbon atoms.
 25. The method of claim 24, wherein the amino-aromaticcompound is 4-aminodiphenylamine.
 26. The method of claim 25, whereinthe acylating agent comprises maleic acid.
 27. The method of claim 25,wherein the acylating agent comprises maleic anhydride.
 28. The methodof claim 18, wherein the amine comprises an amino-aromatic compoundhaving the formula:

in which R₄, R₅ and R₆ are hydrogen or a linear or branched hydrocarbonradical containing from 1 to 10 carbon atoms and the radical is analkyl, alkenyl, alkoxyl, alkyaryl, aryalkyl, hydroxyalkyl, or aminoalkylradical, and R₄, R₅ and R₆ are the same or different.
 29. The method ofclaim 18, wherein the amine comprises an amino-aromatic compoundselected from the group consisting of aminocarbazoles, aminoindoles,amino-indazolinones, aminomercaptotriazole, and aminoperimidines. 30.The method of claim 18, wherein the solvent is suitable for dissolvingthe acylating agent to form a solution.
 31. The method of claim 18,wherein the solvent is suitable for dispersing the acylating agent toform a dispersion.
 32. The method of claim 18, wherein the solvent is anoxygenate.
 33. The method of claim 32, wherein the solvent is acetone.34. The method of claim 18, wherein the solvent is a base oil.
 35. Themethod of claim 18, wherein the solvent is an amide.
 36. The method ofclaim 35, wherein the solvent is N,N-dimethyl formamide.
 37. The methodof claim 18, wherein the amine is combined with the acylating agent allat once.
 38. The method of claim 18, wherein the amine is combined withthe acylating agent as an amine solution or an amine dispersion.
 39. Themethod of claim 18, wherein the amine is added to the acylating agentslowly while stirring the acylating agent.
 40. The method of claim 18,further comprising the step of recovering the reaction product from themixture.
 41. The method of claim 18, wherein the reaction productcomprises a mixture of products suitable for grafting to a polyolefin.42. A method of making a dispersant viscosity index improver, comprisingthe steps of: A. providing (i) a graftable polyolefin, (ii) a reactionproduct of an acylating agent having at least one point of ethylenicunsaturation and an amine, wherein the amine is selected from the groupconsisting of primary amines and secondary amines, and wherein thereaction product is provided in an amount sufficient for a molar ratioof reaction product to polyolefin of at least about 1:1, and (iii) aninitiator in an amount sufficient to graft at least about 1 mole of thereaction product per mole of the polyolefin; B. forming a polyolefinmixture comprising the polyolefin and a solvent; C. adding the reactionproduct to the polyolefin mixture; D. adding the initiator to thepolyolefin mixture; E. heating the polyolefin mixture to at least theinitiation temperature of the initiator; thereby forming a graftcopolymer having a molar ratio of grafted reaction product to polyolefinof at least about 0.5:1.
 43. The method of claim 42, wherein step (A)comprises providing at least about 2 moles of the reaction product permole of the polyolefin, and the method forms a graft copolymer having amolar ratio of grafted reaction product to polyolefin of at least about2:1.
 44. The method of claim 42, wherein step (A) comprises providing atleast about 8 moles of the reaction product per mole of the polyolefin,and the method forms a graft copolymer having a molar ratio of graftedreaction product to polyolefin of at least about 8:1.
 45. The method ofclaim 42, wherein step (A) comprises providing at least about 13 molesof the reaction product per mole of the polyolefin, and the method formsa graft copolymer having a molar ratio of grafted reaction product topolyolefin of at least about 13:1.
 46. The method of claim 42, whereinstep (D) is repeated at least once, thereby increasing the moles of thereaction product grafted onto the polyolefin.
 47. The method of claim42, wherein the polyolefin is dissolved in a solvent, and the solventcomprises a base oil or a light volatile hydrocarbon.
 48. The method ofclaim 47, wherein the solvent contains less than about 50% by weight ofaromatic constituents.
 49. The method of claim 47, wherein the solventcontains less than about 30% by weight of aromatic constituents.
 50. Themethod of claim 47, wherein the solvent contains less than about 25% byweight of aromatic constituents.
 51. The method of claim 47, wherein thesolvent contains less than about 20% by weight of aromatic constituents.52. The method of claim 47, wherein the solvent contains less than about15% by weight of aromatic constituents.
 53. The method of claim 47,wherein the solvent contains less than about 10% by weight of aromaticconstituents.
 54. The method of claim 42, wherein the reaction productis added to the polyolefin mixture substantially simultaneously with theinitiator, at a rate of addition in the range of from about 0.1% perminute to about 100% per minute of the charge of the reaction product.55. The method of claim 42, wherein the initiator is added to thepolyolefin mixture only after substantially all the reaction product hasbeen added to the polyolefin mixture.
 56. The method of claim 42,wherein the initiator is added to the polyolefin mixture atsubstantially the same rate as the reaction product, wherein the rate ismeasured as a percentage of the entire charge added per minute.
 57. Themethod of claim 42, wherein the initiator is added to the polyolefinmixture at a faster rate than the reaction product is added to thepolyolefin mixture, wherein the rate is measured as a percentage of theentire charge added per minute.
 58. The method of claim 42, wherein theinitiator is added to the polyolefin mixture at a slower rate than thereaction product is added to the polyolefin mixture, wherein the rate ismeasured as a percentage of the entire charge added per minute.
 59. Themethod of claim 58, wherein the initiator addition rate and the reactionproduct addition rate are such that there is an excess of reactionproduct present in the polyolefin mixture during essentially the entirereaction.
 60. The method of claim 42, wherein the initiator additionrate and the reaction product addition rate are such that the ratio ofunreacted initiator to unreacted reaction product remains substantiallyconstant during essentially the entire reaction.
 61. The method of claim42, wherein the acylating agent is selected from the group consisting ofmonounsaturated C₄ to C₅₀ dicarboxylic acids; monounsaturated C₃ to C₅₀monocarboxylic acids; anhydrides thereof; and combinations of any of theforegoing.
 62. The method of claim 42, wherein the acylating agent isselected from the group consisting of acrylic acid, crotonic acid,methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconicacid, itaconic anhydride, citraconic acid, citraconic anhydride,mesaconic acid, glutaconic acid, chloromaleic acid, aconitic acid,methylcrotonic acid, sorbic acid, 3-hexenoic acid, 10-decenoic acid,2-pentene-1,3,5-tricarboxylic acid, cinnamic acid, and C₁ to C₄ alkylacid esters of the foregoing, and combinations of the foregoing.
 63. Themethod of claim 42, wherein the acylating agent is maleic acid.
 64. Themethod of claim 42, wherein the acylating agent is maleic anhydride. 65.The method of claim 42, wherein the amine is selected from the groupconsisting of alkyl amines, alkyl polyamines, polyoxyalkylene polyaminesand amino-aromatic compounds.
 66. The method of claim 42, wherein theamine comprises an amino-aromatic compound having the formula:

in which Ar is an aromatic ring, R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a branched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical is an alkyl, alkenyl,alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkyl radical, R₂ is—NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, —CH₂—(CH₂)_(n)—NH₂, or --aryl-NH₂, inwhich n and m each has a value from 1 to 10, and R₃ is hydrogen or analkyl, alkenyl, alkoxyl, aralkyl or alkaryl radical, having from 4 to 24carbon atoms.
 67. The method of claim 66, wherein the amino-aromaticcompound is 4-aminodiphenylamine.
 68. The method of claim 67, whereinthe acylating agent is maleic acid.
 69. The method of claim 67, whereinthe acylating agent is maleic anhydride.
 70. The method of claim 42,wherein the amine comprises an amino-aromatic compound having theformula:

in which R₄, R₅ and R₆ are hydrogen or a linear or branched hydrocarbonradical containing from 1 to 10 carbon atoms and the radical is analkyl, alkenyl, alkoxyl, alkyaryl, aryalkyl, hydroxyalkyl, or aminoalkylradical, and R₄, R₅ and R₆ are the same or different.
 71. The method ofclaim 42, wherein the amine is an amino-aromatic compound is selectedfrom the group consisting of aminocarbazoles, aminoindoles,amino-indazolinones, aminomercaptotriazole, and aminoperimidines.
 72. Amethod of making a graft copolymer which is a graft reaction product ofan ethylenically unsaturated, oxygen- and nitrogen-containing, aliphaticor aromatic reaction product grafted on a polyolefin backbone, themethod comprising the steps of (1) reacting an amine and an acylatingagent having at least one point of ethylenic unsaturation to form areaction product, wherein the amine is selected from the groupconsisting of primary amines and secondary amines, and (2) grafting atleast a portion of the reaction product onto a polyolefin backbone toform a grafted copolymer, wherein the molar proportion of the graftedportion of the reaction product to the polyolefin backbone is at leastabout 0.5:1.
 73. The method of claim 72, wherein said acylating agent isselected from the group consisting of monounsaturated C₄ to C₅₀dicarboxylic acids; monounsaturated C₃ to C₅₀ monocarboxylic acids;anhydrides thereof, and combinations of any of the foregoing.
 74. Themethod of claim 72, wherein the acylating agent is selected from thegroup consisting of acrylic acid, crotonic acid, methacrylic acid,maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconicanhydride, citraconic acid, citraconic anhydride, mesaconic acid,glutaconic acid, chloromaleic acid, aconitic acid, methylcrotonic acid,sorbic acid, 3-hexenoic acid, 10-decenoic acid,2-pentene-1,3,5-tricarboxylic acid, cinnamic acid, and C₁ to C₄ alkylacid esters of the foregoing, and combinations of the foregoing.
 75. Themethod of claim 72, wherein the acylating agent is maleic acid.
 76. Themethod of claim 72, wherein the acylating agent is maleic anhydride. 77.The method of claim 72, wherein the amine is selected from the groupconsisting of alkyl amines, alkyl polyamines, polyoxyalkylene polyaminesand amino-aromatic compounds.
 78. The method of claim 72, wherein theamine comprises an amino-aromatic compound having the formula:

in which Ar is an aromatic ring, R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a branched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical is an alkyl, alkenyl,alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkyl radical, R₂ is—NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, —CH₂—(CH₂)_(n)—NH₂, or -aryl-NH₂, inwhich n and m each has a value from 1 to 10, and R₃ is hydrogen or analkyl, alkenyl, alkoxyl, aralkyl or alkaryl radical, having from 4 to 24carbon atoms.
 79. The method of claim 78, wherein said amino-aromaticcompound is 4-aminodiphenylamine.
 80. The method of claim 72, whereinthe amine comprises an amino-aromatic compound having the formula:

in which R₄, R₅ and R₆ are hydrogen or a linear or branched hydrocarbonradical containing from 1 to 10 carbon atoms and the radical is analkyl, alkenyl, alkoxyl, alkyaryl, aryalkyl, hydroxyalkyl, or aminoalkylradical, and R₄, R₅ and R₆ are the same or different.
 81. The method ofclaim 72, wherein the amine is an amino-aromatic compound selected fromthe group consisting of aminocarbazoles, aminoindoles,amino-indazolinones, aminomercaptotriazole, and aminoperimidines. 82.The method of claim 72, wherein the polyolefin backbone is selected fromthe group consisting of olefin homopolymers, copolymers and terpolymers.83. The method of claim 72, wherein the polyolefin backbone is selectedfrom the group consisting of polyethylene, polypropylene,ethylene-propylene copolymers, and ethylene/propylene/diene copolymers.84. The method of claim 72, wherein the polyolefin backbone is selectedfrom the group consisting of polyisobutene, polymethacrylates,polyalkylstyrenes, partially hydrogenated polyolefins of butadiene andstyrene.
 85. The method of claim 72, wherein the polyolefin backbone isselected from the group consisting of ethylene/propylene/octeneterpolymers, and ethylene/propylene/ ethylidene-norbornene terpolymers,ethylene/propylene/hexadiene terpolymers.
 86. A lubricating oilcomposition comprising: (1) a base oil; and (2) as a dispersantviscosity index improver, a graft copolymer produced by (A) providing anacylating agent having at least one point of ethylenic unsaturation; (B)providing an amine selected from the group consisting of primary aminesand secondary amines; (C) combining the acylating agent and the amine;(D) heating the acylating agent and the amine to form a reactionproduct; (E) providing a graftable polyolefin and an initiator; (F)dissolving said polyolefin in a solvent, forming a solution; (G) addingsaid reaction product to said solution; and (H) adding said initiator tosaid solution; (I) heating said solution to at least the initiationtemperature of said initiator; thereby forming a graft copolymer of saidreaction product on said polyolefin; wherein the dispersant viscosityindex improver is present in the amount sufficient to raise theviscosity index of said base oil by at least about 5 points.
 87. Thelubricating oil composition of claim 86, wherein the dispersantviscosity index improver is present in an amount sufficient to raise theviscosity index of said base oil by at least about 20 points.
 88. Thelubricating oil composition of claim 86, wherein said acylating agent isselected from the group consisting of monounsaturated C₄ to C₅₀dicarboxylic acids; monounsaturated C₃ to C₅₀ monocarboxylic acids;anhydrides thereof, and combinations of any of the foregoing.
 89. Thelubricating oil composition of claim 86, wherein the acylating agent isselected from the group consisting of acrylic acid, crotonic acid,methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconicacid, itaconic anhydride, citraconic acid, citraconic anhydride,mesaconic acid, glutaconic acid, chloromaleic acid, aconitic acid,methylcrotonic acid, sorbic acid, 3-hexenoic acid, 10-decenoic acid,2-pentene-1,3,5-tricarboxylic acid, cinnamic acid, and C₁ to C₄ alkylacid esters of the foregoing, and combinations of the foregoing.
 90. Thelubricating oil composition of claim 86, wherein the acylating agent ismaleic acid.
 91. The lubricating oil composition of claim 86, whereinthe acylating agent is maleic anhydride.
 92. The lubricating oilcomposition of claim 86, wherein the amine is selected from the groupconsisting of alkyl amines, alkyl polyamines, polyoxyalkylene polyaminesand amino-aromatic compounds.
 93. The lubricating oil composition ofclaim 86, wherein the amine comprises an amino-aromatic compound havingthe formula:

in which Ar is an aromatic ring, R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a branched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical is an alkyl, alkenyl,alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkyl radical, R₂ is—NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, —CH₂—(CH₂)_(n)—NH₂, or --aryl--NH₂, inwhich n and m each has a value from 1 to 10, and R₃ is hydrogen or analkyl, alkenyl, alkoxyl, aralkyl or alkaryl radical, having from 4 to 24carbon atoms unless R₃ is hydrogen.
 94. The lubricating oil compositionof claim 93, wherein said amino-aromatic compound is4-aminodiphenylamine.
 95. The lubricating oil composition of claim 94,wherein said acylating agent is maleic acid.
 96. The lubricating oilcomposition of claim 94, wherein said acylating agent is maleicanhydride.
 97. The lubricating oil composition of claim 86, wherein theamine comprises an amino-aromatic compound having the formula:

in which R₄, R₅ and R₆ are hydrogen or a linear or branched hydrocarbonradical containing from 1 to 10 carbon atoms and the radical is analkyl, alkenyl, alkoxyl, alkyaryl, aryalkyl, hydroxyalkyl, or aminoalkylradical, and R₄, R₅ and R₆ are the same or different.
 98. Thelubricating oil composition of claim 86, wherein the amine is anamino-aromatic compound selected from the group consisting ofaminocarbazoles, aminoindoles, amino-indazolinones,aminomercaptotriazole, and aminoperimidines.
 99. A method of making adispersant viscosity index improver, comprising the steps of: A.providing (i) a graftable polyolefin, (ii) a reaction product of anacylating agent having at least one point of ethylenic unsaturation andan amine, wherein the amine is selected from the group consisting ofprimary amines and secondary amines, wherein the reaction product isprovided in an amount sufficient for a molar ratio of reaction productto polyolefin of at least about 0.5:1, and (iii) an amount of aninitiator sufficient to graft at least about I mole of the reactionproduct per mole of the polyolefin; B. melt-reacting a mixtureconsisting essentially of the reaction product, the polyolefin and theinitiator, the melt-reacting step being carried out at a temperature andunder conditions effective to graft the reaction product on at leastsome of the graftable sites of the graftable polyolefin; thereby forminga graft copolymer having at least about 1 mole of the reaction productper mole of the polyolefin.
 100. The method of claim 99, wherein step(A) comprises providing at least about 2 moles of the reaction productper mole of said polyolefin.
 101. The method of claim 99, wherein step(A) comprises providing at least about 8 moles of the reaction productper mole of said polyolefin.
 102. The method of claim 99, wherein step(A) comprises providing at least about 13 moles of the reaction productper mole of said polyolefin.
 103. The method of claim 99, whereinmultiple melt-reaction sites are provided by the melt reactor.
 104. Themethod of claim 99, wherein said acylating agent is selected from thegroup consisting of monounsaturated C₄ to C₅₀ dicarboxylic acids;monounsaturated C₃ to C₅₀ monocarboxylic acids; anhydrides thereof, andcombinations of any of the foregoing.
 105. The method of claim 99,wherein the acylating agent is selected from the group consisting ofacrylic acid, crotonic acid, methacrylic acid, maleic acid, maleicanhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconicacid, citraconic anhydride, mesaconic acid, glutaconic acid,chloromaleic acid, aconitic acid, methylcrotonic acid, sorbic acid,3-hexenoic acid, 10-decenoic acid, 2-pentene-1,3,5-tricarboxylic acid,cinnamic acid, and C₁ to C₄ alkyl acid esters of the foregoing, andcombinations of the foregoing.
 106. The method of claim 99, wherein theacylating agent is maleic acid.
 107. The method of claim 99, wherein theacylating agent is maleic anhydride.
 108. The method of claim 99,wherein the amine is selected from the group consisting of alkyl amines,alkyl polyamines, polyoxyalkylene polyamines and amino-aromaticcompounds.
 109. The method of claim 99, wherein the amine comprises anaminoaromatic compound having the formula:

in which Ar is an aromatic ring, R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a branched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical is an alkyl, alkenyl,alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkyl radical, R₂ is—NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, —CH₂—(CH₂)_(n)—NH₂, or --aryl-NH₂, inwhich n and m each has a value from 1 to 10, and R₃ is hydrogen or analkyl, alkenyl, alkoxyl, aralkyl, or alkaryl radical having from 4 to 24carbon atoms.
 110. The method of claim 110, wherein the amino-aromaticcompound is 4-aminodiphenylamine.
 111. The method of claim 110, whereinthe acylating agent is maleic acid.
 112. The method of claim 110,wherein the acylating agent is maleic anhydride.
 113. The method ofclaim 99, wherein the amine comprises an amino-aromatic compound havingthe formula:

in which R₄, R₅ and R₆ are hydrogen or a linear or branched hydrocarbonradical containing from 1 to 10 carbon atoms and the radical is analkyl, alkenyl, alkoxyl, alkyaryl, aryalkyl, hydroxyalkyl, or aminoalkylradical, and R₄ R₅ and R₆ are the same or different.
 114. The method ofclaim 99, wherein the amine is an amino-aromatic compound is selectedfrom the group consisting of aminocarbazoles, aminoindoles,amino-indazolinones, aminomercaptotriazole, and aminoperimidines. 115.The method of claim 99, wherein the polyolefin is melted before thepolyolefin is mixed with the reaction product and the initiator. 116.The method of claim 115, wherein at least a portion of the reactionproduct is mixed with the polyolefin before the initiator is added tothe polyolefin.
 117. The method of claim 99, wherein the initiator isadded to the polyolefin mixture only after substantially all thereaction product has been added to the polyolefin mixture.
 118. Themethod of claim 99, wherein the initiator is added to the polyolefinmixture at substantially the same rate as the reaction product.
 119. Themethod of claim 99, wherein the initiator is added to the mixture at aslower rate than the reaction product.
 120. The method of claim 99,wherein the melt reacting step is performed in an extruder.
 121. Themethod of claim 120, wherein the reaction product is added in a firstzone of the extruder, and the initiator is added in a second zone of theextruder.
 122. The method of claim 121, wherein the extruder has aplurality of feed points, and the polyolefin, the reaction product, andthe initiator are each fed into separate feed points.
 123. A graftcopolymer generated using a melt-blender having at least about 1 mole ofthe reaction product of an N-arylphenylenediamine and an acylating agentgrafted per mole of a polyolefin, said copolymer having a weight averagemolecular weight of from about 10,000 to about 500,000 and apolydispersity of less than about
 15. 124. The graft copolymer of claim123, having at least about 2 moles of said reaction product per mole ofsaid polyolefin.
 125. The graft copolymer of claim 123, having at leastabout 8 moles of said reaction product per mole of said polyolefin. 126.The graft copolymer of claim 123, having at least about 13 moles of saidreaction product per mole of said polyolefin.
 127. A method of making adispersant viscosity index improver, said method comprising the stepsof: A. providing an acylating agent having at least one point ofethylenic unsaturation; B. providing an amine selected from the groupconsisting of primary amines and secondary amines; C. combining theacylating agent and the amine; D. heating the acylating agent and theamine to form a reaction product; E. providing a graftable polyolefinand an initiator; F. melt-reacting a mixture consisting essentially ofthe reaction product of the acylating agent and the amine with thegraftable polyolefin and the initiator, the melt-reacting step beingcarried out at a temperature and under conditions effective to graft thereaction product on at least some graftable sites of the graftablepolyolefin; thereby forming a graft copolymer of the reaction product onthe polyolefin having at least about 1 mole of the reaction productgrafted per mole of the polyolefin.
 128. The method of claim 127,wherein said acylating agent is selected from the group consisting ofmonounsaturated C₄ to C₅₀ dicarboxylic acids; monounsaturated C₃ to C₅₀monocarboxylic acids; anhydrides thereof, and combinations of any of theforegoing.
 129. The method of claim 129, wherein the acylating agentused for the reaction product is selected from the group consisting ofacrylic acid, crotonic acid, methacrylic acid, maleic acid, maleicanhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconicacid, citraconic anhydride, mesaconic acid, glutaconic acid,chloromaleic acid, aconitic acid, methylcrotonic acid, sorbic acid,3-hexenoic acid, 10-decenoic acid, 2-pentene-1,3,5-tricarboxylic acid,cinnamic acid, and C₁ to C₄ alkyl acid esters of the foregoing, andcombinations of the foregoing.
 130. The method of claim 127, wherein theacylating agent is maleic acid.
 131. The method of claim 127, whereinthe acylating agent is maleic anhydride.
 132. The method of claim 127,wherein said amine is selected from the group consisting of alkylenepolyamines, polyoxyalkylene polyamines, and aminoaromatic compounds.133. The method of claim 127, wherein the amine is selected from thegroup consisting of alkyl amines, alkyl polyamines, polyoxyalkylenepolyamines and amino-aromatic compounds.
 134. The method of claim 127,wherein the amine comprises an amino-aromatic compound having theformula:

in which Ar is an aromatic ring, R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a ranched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical is an alkyl, alkenyl,alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkyl radical, R₂ is—NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, —CH₂—(CH₂)_(n)—NH₂, or --aryl--NH₂, inwhich n and m each has a value from 1 to 10, and R₃ is hydrogen or analkyl, alkenyl, alkoxyl, aralkyl, or alkaryl radical having from 4 to 24carbon atoms.
 135. The method of claim 134, wherein said amino-aromaticcompound is 4-aminodiphenylamine.
 136. The method of claim 127, whereinthe amine comprises an amino-aromatic compound having the formula:

in which R₄, R₅ and R₆ are hydrogen or a linear or branched hydrocarbonradical containing from 1 to 10 carbon atoms and the radical is analkyl, alkenyl, alkoxyl, alkyaryl, aryalkyl, hydroxyalkyl, or aminoalkylradical, and R₄, R₅ and R₆ are the same or different.
 137. The method ofclaim 127, wherein the amine is an amino-aromatic compound selected fromthe group consisting of aminocarbazoles, aminoindoles,amino-indazolinones, aminomercaptotriazole, and aminoperimidines. 138.The method of claim 127, wherein the polyolefin is melted before thepolyolefin is mixed with the reaction product and the initiator. 139.The method of claim 137, wherein at least a portion of the reactionproduct is mixed with the polyolefin before the initiator is mixed withthe polyolefin.
 140. A lubricating oil composition comprising: (1) abase oil; and (2) as a dispersant viscosity index improver, a graftcopolymer produced by (A) providing an acylating agent having at leastone point of ethylenic unsaturation and a solvent; (B) providing anamine selected from the group consisting of primary amines and secondaryamines; (C) combining the acylating agent and the amine; (D) heating theacylating agent and the amine to form a reaction product; (E) providinga graftable polyolefin and an initiator; (F) melt-reacting a mixtureconsisting essentially of the reaction product of the acylating agentand the amine with the graftable polyolefin and the initiator, themelt-reacting step being carried out at a temperature and underconditions effective to graft the reaction product on at least somegraftable sites of the graftable polyolefin; thereby forming a graftcopolymer of the reaction product on the polyolefin; wherein thedispersant viscosity index improver is present in an amount sufficientto raise the viscosity index of the base oil by at least about 5 points.141. The lubricating oil composition method of claim 140, wherein thedispersant viscosity index improver is present in an amount sufficientto raise the viscosity index of said base oil by at least about 20points.
 142. The lubricating oil composition of claim 140, wherein theacylating is from the group consisting of monounsaturated C₄ to C₅₀dicarboxylic acids; monounsaturated C₃ to C₅₀ monocarboxylic acids,anhydrides thereof, and combinations of any of the foregoing.
 143. Thelubricating oil composition of claim 140, wherein the acylating agent isselected from the group consisting of acrylic acid, crotonic acid,methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconicacid, itaconic anhydride, citraconic acid, citraconic anhydride,mesaconic acid, glutaconic acid, chloromaleic acid, aconitic acid,methylcrotonic acid, sorbic acid, 3-hexenoic acid, 10-decenoic acid,2-pentene-1,3,5-tricarboxylic acid, cinnamic acid, and C₁ to C₄ alkylacid esters of the foregoing, and combinations of the foregoing. 144.The lubricating oil composition of claim 140, wherein the acylatingagent is maleic acid.
 145. The lubricating oil composition of claim 140,wherein the acylating agent is maleic anhydride.
 146. The lubricatingoil composition of claim 140, wherein the amine is selected from thegroup consisting of alkyl amines, alkyl polyamines, polyoxyalkylenepolyamines and amino-aromatic compounds.
 147. The lubricating oilcomposition of claim 140, wherein the amine comprises an amino-aromaticcompound having the formula:

in which Ar is an aromatic ring, R₁ is hydrogen, —NH--aryl,—NH--arylalkyl, —NH--alkylaryl, or a branched or straight chain radicalhaving from 4 to 24 carbon atoms and the radical is an alkyl, alkenyl,alkoxyl, arylalkyl, alkylaryl, hydroxyalkyl or aminoalkyl radical, R₂ is—NH₂, —(NH(CH₂)_(n)—)_(m)—NH₂, —CH₂—(CH₂)_(n)—NH₂, or --aryl--NH₂, inwhich n and m each has a value from 1 to 10, and R₃ is hydrogen or analkyl, alkenyl, alkoxyl, aralkyl, or alkaryl radical having from 4 to 24carbon atoms.
 148. The lubricating oil composition of claim 147, whereinthe amino-aromatic compound is 4-aminodiphenylamine.
 149. Thelubricating oil composition of claim 148, wherein the acylating agent ismaleic acid.
 150. The lubricating oil composition of claim 148, whereinthe acylating agent is maleic anhydride.
 151. The lubricating oilcomposition of claim 140, wherein the amine comprises an amino-aromaticcompound having the formula:

in which R₄, R₅ and R₆ are hydrogen or a linear or branched hydrocarbonradical containing from 1 to 10 carbon atoms and the radical is analkyl, alkenyl, alkoxyl, alkyaryl, aryalkyl, hydroxyalkyl, or aminoalkylradical, and R₄, R₅ and R₆ are the same or different.
 152. Thelubricating oil composition of claim 140, wherein the amine is anamino-aromatic compound selected from the group consisting ofaminocarbazoles, aminoindoles, amino-indazolinones,aminomercaptotriazole, and aminoperimidines. 153.Diphenylaminomaleimide.
 154. Mono-diphenylaminoamide of maleic acid.155. The dispersant viscosity index improver produced by the method ofclaim
 42. 156. The graft copolymer produced by the method of claim 72.157. The dispersant viscosity index improver produced by the method ofclaim
 99. 158. The dispersant viscosity index improver produced by themethod of claim 127.